diff --git a/app/models/concerns/discourse_activity_pub/ap/identifier_validations.rb b/app/models/concerns/discourse_activity_pub/ap/identifier_validations.rb
index a83a66f2..e6e3aa56 100644
--- a/app/models/concerns/discourse_activity_pub/ap/identifier_validations.rb
+++ b/app/models/concerns/discourse_activity_pub/ap/identifier_validations.rb
@@ -4,21 +4,16 @@ module AP
     module IdentifierValidations
       extend ActiveSupport::Concern
       include JsonLd
+      include TypeValidations
 
       included do
-        before_validation :ensure_ap_type
         before_validation :ensure_ap_key, if: :local?
         before_validation :ensure_ap_id, if: :local?
 
-        validates :ap_type, presence: true
         validates :ap_key, uniqueness: true, allow_nil: true # foreign objects don't have keys
         validates :ap_id, uniqueness: true, presence: true
       end
 
-      def ap
-        @ap ||= DiscourseActivityPub::AP::Object.get_klass(ap_type)&.new(stored: self)
-      end
-
       def local?
         !!self.local
       end
@@ -27,27 +22,6 @@ def remote?
         !local?
       end
 
-      def _model
-        self.respond_to?(:model) ? self.model : self.actor.model
-      end
-
-      def ensure_ap_type
-        self.ap_type = _model.activity_pub_default_object_type if !self.ap_type
-
-        unless ap
-          self.errors.add(
-            :ap_type,
-            I18n.t(
-              "activerecord.errors.models.discourse_activity_pub_activity.attributes.ap_type.invalid",
-            ),
-          )
-
-          raise ActiveRecord::RecordInvalid
-        end
-
-        self.ap_type = ap.type
-      end
-
       def ensure_ap_key
         self.ap_key = generate_key if !self.ap_key
       end
diff --git a/app/models/concerns/discourse_activity_pub/ap/model_callbacks.rb b/app/models/concerns/discourse_activity_pub/ap/model_callbacks.rb
index 7849527e..e613bb9a 100644
--- a/app/models/concerns/discourse_activity_pub/ap/model_callbacks.rb
+++ b/app/models/concerns/discourse_activity_pub/ap/model_callbacks.rb
@@ -144,6 +144,20 @@ def update_activity_pub_activity_object
         if performing_activity.create? || performing_activity.update?
           performing_activity_object.name = self.activity_pub_name if self.activity_pub_name
           performing_activity_object.content = self.activity_pub_content
+
+          if self.activity_pub_attachments.present?
+            self.activity_pub_attachments.each do |attachment|
+              performing_activity_object.attachments.build(
+                object_id: performing_activity_object.id,
+                object_type: performing_activity_object.class.name,
+                ap_type: attachment.type,
+                url: attachment.url.href,
+                name: attachment.name,
+                media_type: attachment.media_type,
+              )
+            end
+          end
+
           performing_activity_object.save!
         end
       end
diff --git a/app/models/concerns/discourse_activity_pub/ap/type_validations.rb b/app/models/concerns/discourse_activity_pub/ap/type_validations.rb
new file mode 100644
index 00000000..4d3ddd1f
--- /dev/null
+++ b/app/models/concerns/discourse_activity_pub/ap/type_validations.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+module DiscourseActivityPub
+  module AP
+    module TypeValidations
+      extend ActiveSupport::Concern
+
+      included do
+        before_validation :ensure_ap_type
+        validates :ap_type, presence: true
+      end
+
+      def ap
+        @ap ||= DiscourseActivityPub::AP::Object.get_klass(ap_type)&.new(stored: self)
+      end
+
+      def _model
+        self.respond_to?(:model) ? self.model : self.actor.model
+      end
+
+      def ensure_ap_type
+        self.ap_type = _model.activity_pub_default_object_type if !self.ap_type && _model.present?
+
+        unless ap
+          self.errors.add(
+            :ap_type,
+            I18n.t(
+              "activerecord.errors.models.discourse_activity_pub_activity.attributes.ap_type.invalid",
+            ),
+          )
+
+          raise ActiveRecord::RecordInvalid
+        end
+
+        self.ap_type = ap.type
+      end
+    end
+  end
+end
diff --git a/app/models/discourse_activity_pub_attachment.rb b/app/models/discourse_activity_pub_attachment.rb
new file mode 100644
index 00000000..237aa296
--- /dev/null
+++ b/app/models/discourse_activity_pub_attachment.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+class DiscourseActivityPubAttachment < ActiveRecord::Base
+  include DiscourseActivityPub::AP::TypeValidations
+  include DiscourseActivityPub::AP::ObjectValidations
+
+  belongs_to :object, class_name: "DiscourseActivityPubObject", polymorphic: true
+
+  validate :validate_media_type
+
+  protected
+
+  def validate_media_type
+    unless MiniMime.lookup_by_content_type(self.media_type)
+      self.errors.add(
+        :media_type,
+        I18n.t(
+          "activerecord.errors.models.discourse_activity_pub_attachment.attributes.media_type.invalid",
+        ),
+      )
+      raise ActiveRecord::RecordInvalid
+    end
+  end
+end
+
+# == Schema Information
+#
+# Table name: discourse_activity_pub_attachments
+#
+#  id          :bigint           not null, primary key
+#  ap_type     :string           not null
+#  object_id   :bigint           not null
+#  object_type :string           not null
+#  url         :string
+#  name        :string
+#  media_type  :string(200)
+#  created_at  :datetime         not null
+#  updated_at  :datetime         not null
+#
diff --git a/app/models/discourse_activity_pub_object.rb b/app/models/discourse_activity_pub_object.rb
index c35b9576..c0572a71 100644
--- a/app/models/discourse_activity_pub_object.rb
+++ b/app/models/discourse_activity_pub_object.rb
@@ -7,12 +7,21 @@ class DiscourseActivityPubObject < ActiveRecord::Base
 
   belongs_to :model, -> { unscope(where: :deleted_at) }, polymorphic: true, optional: true
   belongs_to :collection, class_name: "DiscourseActivityPubCollection", foreign_key: "collection_id"
+  belongs_to :reply_to,
+             class_name: "DiscourseActivityPubObject",
+             primary_key: "ap_id",
+             foreign_key: "reply_to_id"
+  belongs_to :attributed_to,
+             class_name: "DiscourseActivityPubActor",
+             primary_key: "ap_id",
+             foreign_key: "attributed_to_id"
 
-  has_many :activities, class_name: "DiscourseActivityPubActivity", foreign_key: "object_id"
   has_one :create_activity,
           -> { where(ap_type: DiscourseActivityPub::AP::Activity::Create.type) },
           class_name: "DiscourseActivityPubActivity",
           foreign_key: "object_id"
+
+  has_many :activities, class_name: "DiscourseActivityPubActivity", foreign_key: "object_id"
   has_many :announcements,
            class_name: "DiscourseActivityPubActivity",
            through: :activities,
@@ -21,20 +30,11 @@ class DiscourseActivityPubObject < ActiveRecord::Base
            -> { likes },
            class_name: "DiscourseActivityPubActivity",
            foreign_key: "object_id"
-
-  belongs_to :reply_to,
-             class_name: "DiscourseActivityPubObject",
-             primary_key: "ap_id",
-             foreign_key: "reply_to_id"
   has_many :replies,
            class_name: "DiscourseActivityPubObject",
            primary_key: "ap_id",
            foreign_key: "reply_to_id"
-
-  belongs_to :attributed_to,
-             class_name: "DiscourseActivityPubActor",
-             primary_key: "ap_id",
-             foreign_key: "attributed_to_id"
+  has_many :attachments, class_name: "DiscourseActivityPubAttachment", foreign_key: "object_id"
 
   def url
     if local?
@@ -159,6 +159,10 @@ def attributed_to
     end
   end
 
+  def attachment
+    self.attachments
+  end
+
   def likes_collection
     @likes_collection ||=
       begin
diff --git a/app/serializers/discourse_activity_pub/ap/object/article_serializer.rb b/app/serializers/discourse_activity_pub/ap/object/article_serializer.rb
index 4badb449..ddcfda3e 100644
--- a/app/serializers/discourse_activity_pub/ap/object/article_serializer.rb
+++ b/app/serializers/discourse_activity_pub/ap/object/article_serializer.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class DiscourseActivityPub::AP::Object::ArticleSerializer < DiscourseActivityPub::AP::ObjectSerializer
-  attributes :content, :inReplyTo, :url, :updated
+  attributes :content, :inReplyTo, :url, :updated, :attachment
 
   def inReplyTo
     object.in_reply_to
@@ -18,4 +18,12 @@ def include_content?
   def deleted?
     !object.stored.model || object.stored.model.trashed?
   end
+
+  def attachment
+    object.attachment.map(&:json)
+  end
+
+  def include_attachment?
+    object.attachment.present?
+  end
 end
diff --git a/app/serializers/discourse_activity_pub/ap/object/document_serializer.rb b/app/serializers/discourse_activity_pub/ap/object/document_serializer.rb
new file mode 100644
index 00000000..f7662e7d
--- /dev/null
+++ b/app/serializers/discourse_activity_pub/ap/object/document_serializer.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class DiscourseActivityPub::AP::Object::DocumentSerializer < DiscourseActivityPub::AP::ObjectSerializer
+  attributes :media_type
+end
diff --git a/app/serializers/discourse_activity_pub/ap/object/image_serializer.rb b/app/serializers/discourse_activity_pub/ap/object/image_serializer.rb
new file mode 100644
index 00000000..1cfb059f
--- /dev/null
+++ b/app/serializers/discourse_activity_pub/ap/object/image_serializer.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class DiscourseActivityPub::AP::Object::ImageSerializer < DiscourseActivityPub::AP::ObjectSerializer
+  attributes :media_type
+end
diff --git a/app/serializers/discourse_activity_pub/ap/object/note_serializer.rb b/app/serializers/discourse_activity_pub/ap/object/note_serializer.rb
index bba51c69..5e280bcd 100644
--- a/app/serializers/discourse_activity_pub/ap/object/note_serializer.rb
+++ b/app/serializers/discourse_activity_pub/ap/object/note_serializer.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class DiscourseActivityPub::AP::Object::NoteSerializer < DiscourseActivityPub::AP::ObjectSerializer
-  attributes :content, :inReplyTo, :context
+  attributes :content, :inReplyTo, :context, :attachment
 
   def content
     content = object.content
@@ -30,4 +30,12 @@ def include_content?
   def deleted?
     !object.stored.model || object.stored.model.trashed?
   end
+
+  def attachment
+    object.attachment.map(&:json)
+  end
+
+  def include_attachment?
+    object.attachment.present?
+  end
 end
diff --git a/app/serializers/discourse_activity_pub/ap/object_serializer.rb b/app/serializers/discourse_activity_pub/ap/object_serializer.rb
index e4a5c728..a2f6543c 100644
--- a/app/serializers/discourse_activity_pub/ap/object_serializer.rb
+++ b/app/serializers/discourse_activity_pub/ap/object_serializer.rb
@@ -20,8 +20,9 @@ def attributes(*args)
     hash
   end
 
-  def context
-    object.context
+  def include_id?
+    return false if object.attachment?
+    object.id.present?
   end
 
   def include_context?
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 719a2a2b..f9bd238a 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -21,6 +21,10 @@ en:
             credentials:
               required: "are required"
               invalid: "is not valid"
+        discourse_activity_pub_attachment:
+          attributes:
+            media_type:
+              invalid: "is not valid"
         discourse_activity_pub:
           attributes:
             model_type:
diff --git a/db/migrate/20250319134150_create_discourse_activity_pub_attachments.rb b/db/migrate/20250319134150_create_discourse_activity_pub_attachments.rb
new file mode 100644
index 00000000..9ffd5424
--- /dev/null
+++ b/db/migrate/20250319134150_create_discourse_activity_pub_attachments.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+class CreateDiscourseActivityPubAttachments < ActiveRecord::Migration[7.2]
+  def change
+    create_table :discourse_activity_pub_attachments do |t|
+      t.string :ap_type, null: false
+      t.bigint :object_id, null: false
+      t.string :object_type, null: false
+      t.string :url
+      t.string :name
+      t.string :media_type, limit: 200
+
+      t.timestamps
+    end
+  end
+end
diff --git a/lib/discourse_activity_pub/ap/link.rb b/lib/discourse_activity_pub/ap/link.rb
new file mode 100644
index 00000000..065e3a37
--- /dev/null
+++ b/lib/discourse_activity_pub/ap/link.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+module DiscourseActivityPub
+  module AP
+    class Link
+      attr_accessor :value
+
+      def initialize(value = nil)
+        @value = value
+      end
+
+      def type
+        "Link"
+      end
+
+      def href
+        return value if value.is_a?(String)
+        value[:href] if value.is_a?(Hash)
+      end
+
+      def media_type
+        value[:mediaType] if value.is_a?(Hash)
+      end
+
+      def name
+        value[:name] if value.is_a?(Hash)
+      end
+    end
+  end
+end
diff --git a/lib/discourse_activity_pub/ap/object.rb b/lib/discourse_activity_pub/ap/object.rb
index e5003cf8..dd776628 100644
--- a/lib/discourse_activity_pub/ap/object.rb
+++ b/lib/discourse_activity_pub/ap/object.rb
@@ -7,6 +7,8 @@ class Object
       include HasErrors
       include Handlers
 
+      ATTACHMENT_TYPES = %w[Image Document]
+
       attr_writer :json
       attr_writer :attributed_to
       attr_writer :context
@@ -50,8 +52,16 @@ def actor?
         base_type == "Actor"
       end
 
+      def attachment?
+        ATTACHMENT_TYPES.include?(type)
+      end
+
       def url
-        stored.respond_to?(:url) && stored&.url
+        if stored
+          stored.respond_to?(:url) && stored&.url
+        elsif json.present?
+          Link.new(json[:url])
+        end
       end
 
       def audience
@@ -95,7 +105,11 @@ def summary
       end
 
       def name
-        stored.respond_to?(:name) && stored&.name
+        if stored.present?
+          stored.respond_to?(:name) && stored&.name
+        elsif json.present?
+          json[:name]
+        end
       end
 
       def context
@@ -110,6 +124,17 @@ def delivered_to
         @delivered_to ||= []
       end
 
+      def attachment
+        if stored.respond_to?(:attachment)
+          @attachment ||= (stored.attachment || []).map { |a| a.ap }
+        elsif json.present? && json[:attachment].present?
+          json[:attachment].each_with_object([]) do |attachment_json, result|
+            obj = AP::Object.factory(attachment_json)
+            result << obj if obj.present?
+          end
+        end
+      end
+
       def cache
         @cache ||= {}
       end
diff --git a/lib/discourse_activity_pub/ap/object/document.rb b/lib/discourse_activity_pub/ap/object/document.rb
new file mode 100644
index 00000000..d6571abc
--- /dev/null
+++ b/lib/discourse_activity_pub/ap/object/document.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+module DiscourseActivityPub
+  module AP
+    class Object
+      class Document < Object
+        def type
+          "Document"
+        end
+
+        def media_type
+          if stored && stored.respond_to?(:media_type)
+            stored.media_type
+          elsif json
+            json[:mediaType]
+          end
+        end
+
+        def can_belong_to
+          %i[remote]
+        end
+      end
+    end
+  end
+end
diff --git a/lib/discourse_activity_pub/ap/object/image.rb b/lib/discourse_activity_pub/ap/object/image.rb
new file mode 100644
index 00000000..91baab00
--- /dev/null
+++ b/lib/discourse_activity_pub/ap/object/image.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+module DiscourseActivityPub
+  module AP
+    class Object
+      class Image < Object
+        def type
+          "Image"
+        end
+
+        def media_type
+          if stored && stored.respond_to?(:media_type)
+            stored.media_type
+          elsif json
+            json[:mediaType]
+          end
+        end
+
+        def can_belong_to
+          %i[remote]
+        end
+      end
+    end
+  end
+end
diff --git a/lib/discourse_activity_pub/post_handler.rb b/lib/discourse_activity_pub/post_handler.rb
index ca75ac08..bf58b4ee 100644
--- a/lib/discourse_activity_pub/post_handler.rb
+++ b/lib/discourse_activity_pub/post_handler.rb
@@ -31,7 +31,7 @@ def create(
       return nil if !import_mode && !new_topic && !reply_to && !topic_id
 
       params = {
-        raw: object.content,
+        raw: build_post_raw,
         skip_events: true,
         skip_validations: true,
         skip_jobs: true,
@@ -149,6 +149,25 @@ def self.ensure_activity_has_post(activity)
 
     protected
 
+    def supported_image?(media_type)
+      extension = MiniMime.lookup_by_content_type(media_type)&.extension
+      FileHelper.supported_images.include?(extension)
+    end
+
+    def build_post_raw
+      raw = object.content
+      if object.attachments.present?
+        object.attachments.each do |attachment|
+          raw += attached_image_html(attachment) if supported_image?(attachment.media_type)
+        end
+      end
+      raw
+    end
+
+    def attached_image_html(attachment)
+      "\n<img src=\"#{attachment.url}\" alt=\"#{attachment.name}\"/>"
+    end
+
     def can_create_topic?(category)
       category&.activity_pub_ready?
     end
diff --git a/plugin.rb b/plugin.rb
index 33d95412..ba5c63cc 100644
--- a/plugin.rb
+++ b/plugin.rb
@@ -49,6 +49,7 @@
   require_relative "lib/discourse_activity_pub/context_resolver"
   require_relative "lib/discourse_activity_pub/ap"
   require_relative "lib/discourse_activity_pub/ap/handlers"
+  require_relative "lib/discourse_activity_pub/ap/link"
   require_relative "lib/discourse_activity_pub/ap/object"
   require_relative "lib/discourse_activity_pub/ap/actor"
   require_relative "lib/discourse_activity_pub/ap/actor/group"
@@ -70,11 +71,14 @@
   require_relative "lib/discourse_activity_pub/ap/activity/like"
   require_relative "lib/discourse_activity_pub/ap/object/note"
   require_relative "lib/discourse_activity_pub/ap/object/article"
+  require_relative "lib/discourse_activity_pub/ap/object/document"
+  require_relative "lib/discourse_activity_pub/ap/object/image"
   require_relative "lib/discourse_activity_pub/ap/collection"
   require_relative "lib/discourse_activity_pub/ap/collection/collection_page"
   require_relative "lib/discourse_activity_pub/ap/collection/ordered_collection_page"
   require_relative "lib/discourse_activity_pub/ap/collection/ordered_collection"
   require_relative "lib/discourse_activity_pub/admin"
+  require_relative "app/models/concerns/discourse_activity_pub/ap/type_validations"
   require_relative "app/models/concerns/discourse_activity_pub/ap/identifier_validations"
   require_relative "app/models/concerns/discourse_activity_pub/ap/object_validations"
   require_relative "app/models/concerns/discourse_activity_pub/ap/model_validations"
@@ -90,6 +94,7 @@
   require_relative "app/models/discourse_activity_pub_log"
   require_relative "app/models/discourse_activity_pub_object"
   require_relative "app/models/discourse_activity_pub_collection"
+  require_relative "app/models/discourse_activity_pub_attachment"
   require_relative "app/jobs/discourse_activity_pub_process"
   require_relative "app/jobs/discourse_activity_pub_deliver"
   require_relative "app/jobs/discourse_activity_pub_log_rotate"
@@ -135,6 +140,8 @@
   require_relative "app/serializers/discourse_activity_pub/ap/actor/person_serializer"
   require_relative "app/serializers/discourse_activity_pub/ap/object/note_serializer"
   require_relative "app/serializers/discourse_activity_pub/ap/object/article_serializer"
+  require_relative "app/serializers/discourse_activity_pub/ap/object/image_serializer"
+  require_relative "app/serializers/discourse_activity_pub/ap/object/document_serializer"
   require_relative "app/serializers/discourse_activity_pub/ap/collection_serializer"
   require_relative "app/serializers/discourse_activity_pub/ap/collection/ordered_collection_serializer"
   require_relative "app/serializers/discourse_activity_pub/about_serializer"
@@ -550,6 +557,19 @@
     @activity_pub_topic_trashed ||= Topic.with_deleted.find_by(id: self.topic_id)
   end
   add_to_class(:post, :activity_pub_object_id) { activity_pub_object&.ap_id }
+  add_to_class(:post, :activity_pub_attachments) do
+    uploads
+      .where(extension: FileHelper.supported_images)
+      .map do |upload|
+        DiscourseActivityPub::AP::Object::Image.new(
+          json: {
+            name: upload.original_filename,
+            url: UrlHelper.absolute(upload.url),
+            mediaType: MiniMime.lookup_by_extension(upload.extension).content_type,
+          },
+        )
+      end
+  end
 
   add_model_callback(:post, :after_destroy) do
     # We need these to create a Delete activity when the post is actually destroyed
@@ -1166,6 +1186,32 @@
                     object_id: object.json[:id],
                   )
           end
+
+          if object.json[:attachment].present?
+            object.json[:attachment].each do |json|
+              attachment = DiscourseActivityPub::AP::Object.factory(json)
+              if attachment
+                # Some platforms (e.g. Mastodon) put attachment url media types on the attachment itself,
+                # instead of on a Link object in the url attribute. Technically this violates the specification,
+                # but we need to support it nevertheless. See further https://www.w3.org/TR/activitystreams-vocabulary/#dfn-mediatype
+                media_type = attachment.url.media_type || attachment.media_type
+                name = attachment.url.name || attachment.name
+
+                begin
+                  DiscourseActivityPubAttachment.create(
+                    object_id: object.stored.id,
+                    object_type: "DiscourseActivityPubObject",
+                    ap_type: attachment.type,
+                    url: attachment.url.href,
+                    name: name,
+                    media_type: media_type,
+                  )
+                rescue ActiveRecord::RecordInvalid => error
+                  # fail silently if an attachment does not validate
+                end
+              end
+            end
+          end
         end
       end
     end
diff --git a/spec/fabricators/discourse_activity_pub_attachment_fabricator.rb b/spec/fabricators/discourse_activity_pub_attachment_fabricator.rb
new file mode 100644
index 00000000..1d236012
--- /dev/null
+++ b/spec/fabricators/discourse_activity_pub_attachment_fabricator.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+Fabricator(:discourse_activity_pub_attachment) do
+  ap_type { "Image" }
+  media_type { "image/png" }
+
+  before_create do |object|
+    filename = "#{SecureRandom.hex(8)}-image"
+    object.url = "https://local.com/attachment/image/#{filename}.png"
+    object.name = filename
+  end
+end
diff --git a/spec/jobs/discourse_activity_pub_deliver_spec.rb b/spec/jobs/discourse_activity_pub_deliver_spec.rb
index b7ea0da6..86e11926 100644
--- a/spec/jobs/discourse_activity_pub_deliver_spec.rb
+++ b/spec/jobs/discourse_activity_pub_deliver_spec.rb
@@ -335,6 +335,29 @@ def find_announce
           end
         end
       end
+
+      context "when object has attachments" do
+        let!(:topic) { Fabricate(:topic, category: group.model) }
+        let!(:post) { Fabricate(:post, topic: topic) }
+        let!(:note) { Fabricate(:discourse_activity_pub_object_note, local: true, model: post) }
+        let!(:attachment1) { Fabricate(:discourse_activity_pub_attachment, object: note) }
+        let!(:attachment2) { Fabricate(:discourse_activity_pub_attachment, object: note) }
+        let!(:activity) do
+          Fabricate(:discourse_activity_pub_activity_create, object: note, actor: group)
+        end
+
+        it "publishes the attachments" do
+          json = published_json(activity)
+          expect(json[:object][:attachment].size).to eq(2)
+          expect(json[:object][:attachment].first[:url]).to eq(attachment1.url)
+          expect(json[:object][:attachment].second[:url]).to eq(attachment2.url)
+        end
+
+        it "performs the right request" do
+          expect_request(body: published_json(activity), actor_id: group.id, uri: person.inbox)
+          execute_job(object_id: activity.id, from_actor_id: activity.actor.id)
+        end
+      end
     end
   end
 end
diff --git a/spec/lib/discourse_activity_pub/ap/activity/create_spec.rb b/spec/lib/discourse_activity_pub/ap/activity/create_spec.rb
index 9e4c9405..8c8e5b10 100644
--- a/spec/lib/discourse_activity_pub/ap/activity/create_spec.rb
+++ b/spec/lib/discourse_activity_pub/ap/activity/create_spec.rb
@@ -426,5 +426,241 @@
         end
       end
     end
+
+    context "with a Note with attachments" do
+      let!(:delivered_to) { category.activity_pub_actor.ap_id }
+      let!(:follow) do
+        Fabricate(
+          :discourse_activity_pub_follow,
+          follower: category.activity_pub_actor,
+          followed: actor,
+        )
+      end
+
+      before { stub_object_request(actor) }
+
+      context "with supported attachment types" do
+        let!(:attachment_url_1) { "https://example.com/files/cats.png" }
+        let!(:attachment_url_2) { "https://example.com/files/dogs.jpeg" }
+        let!(:attachment_url_3) { "https://example.com/files/autodesk-dog.3ds" }
+        let!(:attachment_name_1) { "A cool cat" }
+        let!(:attachments_with_supported_mediatypes) do
+          [
+            {
+              type: "Document",
+              mediaType: "image/png",
+              url: attachment_url_1,
+              name: attachment_name_1,
+            },
+            { type: "Image", mediaType: "image/jpeg", url: attachment_url_2 },
+          ]
+        end
+        let!(:attachments_with_unsupported_mediatypes) do
+          [
+            {
+              type: "Document",
+              mediaType: "image/png",
+              url: attachment_url_1,
+              name: attachment_name_1,
+            },
+            { type: "Image", mediaType: "image/x-3ds", url: attachment_url_3 },
+          ]
+        end
+        let!(:attachments_with_invalid_mediatypes) do
+          [
+            {
+              type: "Document",
+              mediaType: "image/png",
+              url: attachment_url_1,
+              name: attachment_name_1,
+            },
+            { type: "Image", mediaType: "invalid-type", url: attachment_url_3 },
+          ]
+        end
+        let!(:attachments_with_link_objects) do
+          [
+            {
+              type: "Document",
+              url: {
+                type: "Link",
+                href: attachment_url_1,
+                mediaType: "image/png",
+                name: attachment_name_1,
+              },
+            },
+            { type: "Image", mediaType: "image/jpeg", url: attachment_url_2 },
+          ]
+        end
+
+        context "with supported media types" do
+          let!(:new_post_json) do
+            build_activity_json(
+              actor: actor,
+              object:
+                build_object_json(
+                  name: "My cool topic title",
+                  attributed_to: actor,
+                  attachments: attachments_with_supported_mediatypes,
+                ),
+              type: "Create",
+            )
+          end
+
+          it "creates records for all attachments" do
+            perform_process(new_post_json, delivered_to)
+            object =
+              DiscourseActivityPubObject.find_by(ap_type: "Note", attributed_to_id: actor.ap_id)
+            expect(object.attachments.size).to eq(2)
+            expect(object.attachments.first.ap_type).to eq("Document")
+            expect(object.attachments.first.url).to eq(attachment_url_1)
+            expect(object.attachments.first.media_type).to eq("image/png")
+            expect(object.attachments.second.ap_type).to eq("Image")
+            expect(object.attachments.second.url).to eq(attachment_url_2)
+            expect(object.attachments.second.media_type).to eq("image/jpeg")
+          end
+
+          it "adds the attachment urls the post" do
+            perform_process(new_post_json, delivered_to)
+            post =
+              Post.find_by(
+                raw:
+                  "#{new_post_json[:object][:content]}\n<img src=\"#{attachment_url_1}\" alt=\"#{attachment_name_1}\"/>\n<img src=\"#{attachment_url_2}\" alt=\"\"/>",
+              )
+            expect(post.present?).to be(true)
+          end
+        end
+
+        context "with supported and unsupported media types" do
+          let!(:new_post_json) do
+            build_activity_json(
+              actor: actor,
+              object:
+                build_object_json(
+                  name: "My cool topic title",
+                  attributed_to: actor,
+                  attachments: attachments_with_unsupported_mediatypes,
+                ),
+              type: "Create",
+            )
+          end
+
+          it "creates records for all attachments" do
+            perform_process(new_post_json, delivered_to)
+            object =
+              DiscourseActivityPubObject.find_by(ap_type: "Note", attributed_to_id: actor.ap_id)
+            expect(object.attachments.size).to eq(2)
+            expect(object.attachments.first.ap_type).to eq("Document")
+            expect(object.attachments.first.url).to eq(attachment_url_1)
+            expect(object.attachments.first.media_type).to eq("image/png")
+            expect(object.attachments.second.ap_type).to eq("Image")
+            expect(object.attachments.second.url).to eq(attachment_url_3)
+            expect(object.attachments.second.media_type).to eq("image/x-3ds")
+          end
+
+          it "adds urls for attachments with supported media types to the post" do
+            perform_process(new_post_json, delivered_to)
+            post =
+              Post.find_by(
+                raw:
+                  "#{new_post_json[:object][:content]}\n<img src=\"#{attachment_url_1}\" alt=\"#{attachment_name_1}\"/>",
+              )
+            expect(post.present?).to be(true)
+          end
+        end
+
+        context "with supported and invalid media types" do
+          let!(:new_post_json) do
+            build_activity_json(
+              actor: actor,
+              object:
+                build_object_json(
+                  name: "My cool topic title",
+                  attributed_to: actor,
+                  attachments: attachments_with_invalid_mediatypes,
+                ),
+              type: "Create",
+            )
+          end
+
+          it "creates records for attachments with valid media types" do
+            perform_process(new_post_json, delivered_to)
+            object =
+              DiscourseActivityPubObject.find_by(ap_type: "Note", attributed_to_id: actor.ap_id)
+            expect(object.attachments.size).to eq(1)
+            expect(object.attachments.first.ap_type).to eq("Document")
+            expect(object.attachments.first.url).to eq(attachment_url_1)
+            expect(object.attachments.first.media_type).to eq("image/png")
+          end
+
+          it "adds urls for attachments with supported media types to the post" do
+            perform_process(new_post_json, delivered_to)
+            post =
+              Post.find_by(
+                raw:
+                  "#{new_post_json[:object][:content]}\n<img src=\"#{attachment_url_1}\" alt=\"#{attachment_name_1}\"/>",
+              )
+            expect(post.present?).to be(true)
+          end
+        end
+
+        context "with Link objects" do
+          let!(:new_post_json) do
+            build_activity_json(
+              actor: actor,
+              object:
+                build_object_json(
+                  name: "My cool topic title",
+                  attributed_to: actor,
+                  attachments: attachments_with_link_objects,
+                ),
+              type: "Create",
+            )
+          end
+
+          it "creates records for all attachments" do
+            perform_process(new_post_json, delivered_to)
+            object =
+              DiscourseActivityPubObject.find_by(ap_type: "Note", attributed_to_id: actor.ap_id)
+            expect(object.attachments.size).to eq(2)
+            expect(object.attachments.first.ap_type).to eq("Document")
+            expect(object.attachments.first.url).to eq(attachment_url_1)
+            expect(object.attachments.first.media_type).to eq("image/png")
+            expect(object.attachments.second.ap_type).to eq("Image")
+            expect(object.attachments.second.url).to eq(attachment_url_2)
+            expect(object.attachments.second.media_type).to eq("image/jpeg")
+          end
+        end
+      end
+
+      context "with unsupported attachment types" do
+        let!(:object_with_unsupported_attachment_json) do
+          build_object_json(
+            name: "My cool topic title",
+            attributed_to: actor,
+            attachments: [
+              { type: "PropertyValue", name: "Homepage", value: "https://myhomepage.com" },
+            ],
+          )
+        end
+        let!(:new_post_json) do
+          build_activity_json(
+            actor: actor,
+            object: object_with_unsupported_attachment_json,
+            type: "Create",
+          )
+        end
+
+        it "does not create attachments" do
+          expect { perform_process(new_post_json, delivered_to) }.not_to change {
+            DiscourseActivityPubAttachment.count
+          }
+        end
+
+        it "does not add anything to the post" do
+          perform_process(new_post_json, delivered_to)
+          expect(Post.exists?(raw: new_post_json[:object][:content])).to be(true)
+        end
+      end
+    end
   end
 end
diff --git a/spec/models/post_spec.rb b/spec/models/post_spec.rb
index 230966fd..3153767b 100644
--- a/spec/models/post_spec.rb
+++ b/spec/models/post_spec.rb
@@ -2817,5 +2817,56 @@ def perform_delete
         end
       end
     end
+
+    context "with uploads" do
+      let!(:topic) { Fabricate(:topic, category: category) }
+      let!(:user) { Fabricate(:user) }
+
+      before do
+        toggle_activity_pub(category, publication_type: "full_topic")
+        topic.create_activity_pub_collection!
+      end
+
+      def perform_create
+        post.perform_activity_pub_activity(:create)
+        post.reload
+      end
+
+      context "with a supported media type" do
+        let!(:post) { Fabricate(:post_with_uploaded_image, topic: topic) }
+
+        before do
+          DiscourseActivityPub::ActorHandler.update_or_create_actor(post.user)
+          post.link_post_uploads
+        end
+
+        it "creates attachments" do
+          perform_create
+          expect(post.activity_pub_object.attachments.size).to eq(1)
+          expect(post.activity_pub_object.attachments.first.ap_type).to eq("Image")
+          expect(post.activity_pub_object.attachments.first.name).to eq(
+            post.uploads.first.original_filename,
+          )
+          expect(post.activity_pub_object.attachments.first.media_type).to eq("image/png")
+          expect(post.activity_pub_object.attachments.first.url).to eq(
+            UrlHelper.absolute(post.uploads.first.url),
+          )
+        end
+      end
+
+      context "with an unsupported media type" do
+        let!(:post) { Fabricate(:post_with_an_attachment, topic: topic) }
+
+        before do
+          DiscourseActivityPub::ActorHandler.update_or_create_actor(post.user)
+          post.link_post_uploads
+        end
+
+        it "does not create attachments" do
+          perform_create
+          expect(post.activity_pub_object.attachments.size).to eq(0)
+        end
+      end
+    end
   end
 end
diff --git a/spec/multisite/activity_pub_multisite_spec.rb b/spec/multisite/activity_pub_multisite_spec.rb
index ca1cbfc9..a86c5c28 100644
--- a/spec/multisite/activity_pub_multisite_spec.rb
+++ b/spec/multisite/activity_pub_multisite_spec.rb
@@ -21,6 +21,10 @@ def process_case(actor)
       stub_object_request(read_integration_json("case_2", "actor_2"))
       stub_object_request(read_integration_json("case_2", "actor_3"))
       stub_object_request(read_integration_json("case_2", "context_1"))
+      stub_request(
+        :get,
+        "https://community.nodebb.org/assets/uploads/files/1738535378096-1000007220.jpg",
+      ).to_return(status: 200)
 
       6.times do |index|
         process_json(read_integration_json("case_2", "received_#{index + 1}"), actor)
diff --git a/spec/plugin_helper.rb b/spec/plugin_helper.rb
index 05469f9d..d85f361b 100644
--- a/spec/plugin_helper.rb
+++ b/spec/plugin_helper.rb
@@ -150,7 +150,8 @@ def build_object_json(
   cc: nil,
   audience: nil,
   attributed_to: nil,
-  context: nil
+  context: nil,
+  attachments: []
 )
   _json = {
     "@context": "https://www.w3.org/ns/activitystreams",
@@ -173,6 +174,7 @@ def build_object_json(
     attributed_to
   end
   _json[:context] = context if context
+  _json[:attachment] = attachments if attachments.present?
   _json.with_indifferent_access
 end