diff --git a/modules/nf-core/pbmarkdup/environment.yml b/modules/nf-core/pbmarkdup/environment.yml
new file mode 100644
index 00000000000..7e5a3099a71
--- /dev/null
+++ b/modules/nf-core/pbmarkdup/environment.yml
@@ -0,0 +1,7 @@
+---
+# yaml-language-server: $schema=https://raw.githubusercontent.com/sanger-tol/nf-core-modules/master/modules/environment-schema.json
+channels:
+  - conda-forge
+  - bioconda
+dependencies:
+  - bioconda::pbmarkdup=1.2.0
diff --git a/modules/nf-core/pbmarkdup/main.nf b/modules/nf-core/pbmarkdup/main.nf
new file mode 100644
index 00000000000..20da004d21b
--- /dev/null
+++ b/modules/nf-core/pbmarkdup/main.nf
@@ -0,0 +1,73 @@
+process PBMARKDUP {
+    tag "$meta.id"
+    label "process_high"
+
+    conda "${moduleDir}/environment.yml"
+    container "${ workflow.containerEngine == 'singularity' && !task.ext.singularity_pull_docker_container ?
+        'https://depot.galaxyproject.org/singularity/pbmarkdup:1.2.0--h9ee0642_0' :
+        'biocontainers/pbmarkdup:1.2.0--h9ee0642_0' }"
+
+    input:
+    tuple val(meta), path(input)
+
+    output:
+    tuple val(meta), path("${prefix}.${suffix}"), emit: markduped
+    tuple val(meta), path("${dupfile_name}")    , emit: dupfile   , optional: true
+    tuple val(meta), path("*.pbmarkdup.log")    , emit: log       , optional: true
+    path "versions.yml"                         , emit: versions
+
+    when:
+    task.ext.when == null || task.ext.when
+
+    script:
+    def args     = task.ext.args  ?: ''
+    prefix       = task.ext.prefix ?: "${meta.id}"
+    suffix       = input[0].getExtension()             // To allow multiple input types
+    dupfile_name = args.contains('--dup-file') ? (args =~ /--dup-file\s+(\S+)/)[0][1] : ''
+    def log_args = args.contains('--log-level') ? " > ${prefix}.pbmarkdup.log" : ''
+    def file_list = input.collect { it.getName() }.join(' ')
+
+    // Check file name collisions between input, output, and duplicate file
+    if (file_list.contains("${prefix}.${suffix}"))
+        error """Output file `${prefix}.${suffix}` conflicts with an input file.
+        Please change the output `$prefix` or input file names."""
+    if (dupfile_name) {
+        if (file_list.contains(dupfile_name))
+            error """Duplicate file `$dupfile_name` conflicts with an input file.
+            Please change the duplicate file name `$dupfile_name` or input file names."""
+
+        if (dupfile_name == "${prefix}.${suffix}")
+            error """Duplicate file `$dupfile_name` cannot be the same as the output file name.
+            Please change the duplicate file name `$dupfile_name` or output prefix `$prefix`."""
+    }
+
+    """
+    pbmarkdup \\
+        -j ${task.cpus} \\
+        ${file_list} \\
+        ${prefix}.${suffix} \\
+        $args \\
+        ${log_args}
+
+    cat <<-END_VERSIONS > versions.yml
+    "${task.process}":
+        pbmarkdup: \$(echo \$(pbmarkdup --version 2>&1) | awk 'BEFORE{FS=" "}{print \$2}')
+    END_VERSIONS
+    """
+
+    stub:
+    def args      = task.ext.args  ?: ''
+    prefix        = task.ext.prefix ?: "${meta.id}"
+    suffix        = input[0].getExtension()             // To allow multiple input types
+    dupfile_name  = args.contains('--dup-file') ? (args =~ /--dup-file\s+(\S+)/)[0][1] : ''
+    def log_args  = args.contains('--log-level') ? " > ${prefix}.pbmarkdup.log" : ''
+    def file_list = input.collect { it.getName() }.join(' ')
+    """
+    touch ${prefix}.${suffix}
+
+    cat <<-END_VERSIONS > versions.yml
+    "${task.process}":
+        pbmarkdup: \$(echo \$(pbmarkdup --version 2>&1) | awk 'BEFORE{FS=" "}{print \$2}')
+    END_VERSIONS
+    """
+}
diff --git a/modules/nf-core/pbmarkdup/meta.yml b/modules/nf-core/pbmarkdup/meta.yml
new file mode 100644
index 00000000000..59a1de05425
--- /dev/null
+++ b/modules/nf-core/pbmarkdup/meta.yml
@@ -0,0 +1,90 @@
+# yaml-language-server: $schema=https://raw.githubusercontent.com/nf-core/modules/master/modules/meta-schema.json
+name: "pbmarkdup"
+description: |
+  Takes one or multiple sequencing chips of an amplified library as HiFi reads and marks or removes
+  duplicates.
+keywords:
+  - markdup
+  - bam
+  - fastq
+  - fasta
+tools:
+  - pbmarkdup:
+      description: |
+        pbmarkdup identifies and marks duplicate reads in PacBio HiFi (CCS) data. It clusters
+        highly similar CCS reads to detect PCR duplicates and flags them in the output files
+        (BAM,FASTQ,FASTA) (duplicate bit 0x400), optionally removing duplicates.
+        (duplicate bit 0x400), optionally removing duplicates.
+      homepage: https://github.com/PacificBiosciences/pbmarkdup
+      documentation: https://github.com/PacificBiosciences/pbmarkdup
+      licence: ["BSD-3-Clause"]
+      identifier: biotools:pbmarkdup
+input:
+  - - meta:
+        type: map
+        description: |
+          Groovy Map containing sample information
+          e.g. `[ id:'sample1' ]`
+    - input:
+        type: file
+        description: |
+          Sequencing reads in BAM, FASTQ, or FASTA format.
+        pattern: "*.{bam,f*a,/.*f.*\\.gz/}"
+        ontologies:
+          - edam: http://edamontology.org/format_2546 # FASTA-like
+          - edam: "http://edamontology.org/format_1930" # FASTQ
+          - edam: "http://edamontology.org/format_2572" # BAM
+output:
+  markduped:
+    - - meta:
+          type: map
+          description: |
+            Groovy Map containing sample information
+            e.g. `[ id:'sample1' ]`
+      - ${prefix}.${suffix}:
+          type: file
+          description: |
+            Markduplicated sequencing reads in the same format as the input file.
+          pattern: "*.{bam,f*a,/.*f.*\\.gz/}"
+          ontologies:
+            - edam: http://edamontology.org/format_2546 # FASTA-like
+            - edam: "http://edamontology.org/format_1930" # FASTQ
+            - edam: "http://edamontology.org/format_2572" # BAM
+  dupfile:
+    - - meta:
+          type: map
+          description: |
+            Groovy Map containing sample information
+            e.g. `[ id:'sample1' ]`
+      - ${dupfile_name}:
+          type: file
+          description: |
+            (Optional) File listing duplicate reads (Specify by --dup-file).
+          pattern: "*.{bam,f*a,/.*f.*\\.gz/}"
+          ontologies:
+            - edam: http://edamontology.org/format_2546 # FASTA-like
+            - edam: "http://edamontology.org/format_1930" # FASTQ
+            - edam: "http://edamontology.org/format_2572" # BAM
+  log:
+    - - meta:
+          type: map
+          description: |
+            Groovy Map containing sample information
+            e.g. `[ id:'sample1' ]`
+      - "*.pbmarkdup.log":
+          type: file
+          description: |
+            Log file generated by pbmarkdup (if --log-level is specified).
+          pattern: "*.pbmarkdup.log"
+          ontologies: []
+  versions:
+    - versions.yml:
+        type: file
+        description: File containing software versions
+        pattern: "versions.yml"
+        ontologies:
+          - edam: http://edamontology.org/format_3750 # YAML
+authors:
+  - "@sainsachiko"
+maintainers:
+  - "@sainsachiko"
diff --git a/modules/nf-core/pbmarkdup/tests/main.nf.test b/modules/nf-core/pbmarkdup/tests/main.nf.test
new file mode 100644
index 00000000000..dbe78c3517c
--- /dev/null
+++ b/modules/nf-core/pbmarkdup/tests/main.nf.test
@@ -0,0 +1,133 @@
+
+nextflow_process {
+
+    name "Test Process PBMARKDUP"
+    script "../main.nf"
+    process "PBMARKDUP"
+
+    tag "modules"
+    tag "modules_nfcore"
+    tag "pbmarkdup"
+
+    config './nextflow.config'
+
+    test("deilephila porcellus - fasta") {
+
+        when {
+
+            params {
+                pbmarkdup_args = "--clobber"
+            }
+
+            process {
+                """
+                input[0] = Channel.of(
+                    [
+                        [ id:'test' ], // meta map
+                        file(params.modules_testdata_base_path + 'genomics/eukaryotes/deilephila_porcellus/mito/ilDeiPorc1.HiFi.reads.fa', checkIfExists: true)
+                    ]
+                )
+                """
+            }
+        }
+
+        then {
+            assertAll(
+                { assert process.success },
+                { assert snapshot(process.out).match() }
+            )
+        }
+
+    }
+
+    test("acropora cervicornis - bam - multiple tests with dupfile and log") {
+        when {
+
+            params {
+                pbmarkdup_args = "--clobber --dup-file ${prefix}.dup.bam --log-level INFO"
+            }
+
+            process {
+                """
+                input[0] = Channel.of(
+                    [
+                        [ id:'test' ], // meta map
+                        [ file(params.modules_testdata_base_path + 'genomics/eukaryotes/acropora_cervicornis/m84093_241116_151316_s2.hifi_reads.bc2028.subset.1.bam', checkIfExists: true),
+                          file(params.modules_testdata_base_path + 'genomics/eukaryotes/acropora_cervicornis/m84093_241116_151316_s2.hifi_reads.bc2028.subset.2.bam', checkIfExists: true)
+                        ]
+                    ]
+                )
+                """
+            }
+        }
+
+        then {
+            assertAll(
+                { assert process.success },
+                { assert snapshot(process.out).match() }
+            )
+        }
+
+    }
+
+    test("acropora cervicornis - bam - multiple tests remove duplicates") {
+        when {
+
+            params {
+                pbmarkdup_args = "--clobber --rmdup"
+            }
+
+            process {
+                """
+                input[0] = Channel.of(
+                    [
+                        [ id:'test' ], // meta map
+                        [ file(params.modules_testdata_base_path + 'genomics/eukaryotes/acropora_cervicornis/m84093_241116_151316_s2.hifi_reads.bc2028.subset.1.bam', checkIfExists: true),
+                          file(params.modules_testdata_base_path + 'genomics/eukaryotes/acropora_cervicornis/m84093_241116_151316_s2.hifi_reads.bc2028.subset.2.bam', checkIfExists: true)
+                        ]
+                    ]
+                )
+                """
+            }
+        }
+
+        then {
+            assertAll(
+                { assert process.success },
+                { assert snapshot(process.out).match() }
+            )
+        }
+
+    }
+
+    test("deilephila porcellus - stub") {
+
+        options "-stub"
+
+        when {
+            params {
+                pbmarkdup_args = ""
+            }
+
+            process {
+                """
+                input[0] = Channel.of(
+                    [
+                        [ id:'test' ], // meta map
+                        file(params.modules_testdata_base_path + 'genomics/eukaryotes/deilephila_porcellus/mito/ilDeiPorc1.HiFi.reads.fa', checkIfExists: true)
+                    ]
+                )
+                """
+            }
+        }
+
+        then {
+            assertAll(
+                { assert process.success },
+                { assert snapshot(process.out).match() }
+            )
+        }
+
+    }
+
+}
diff --git a/modules/nf-core/pbmarkdup/tests/main.nf.test.snap b/modules/nf-core/pbmarkdup/tests/main.nf.test.snap
new file mode 100644
index 00000000000..705b7dd4f2a
--- /dev/null
+++ b/modules/nf-core/pbmarkdup/tests/main.nf.test.snap
@@ -0,0 +1,202 @@
+{
+    "acropora cervicornis - bam - multiple tests remove duplicates": {
+        "content": [
+            {
+                "0": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.bam:md5,86e22a794d904cc48cb3758a03883ba1"
+                    ]
+                ],
+                "1": [
+                    
+                ],
+                "2": [
+                    
+                ],
+                "3": [
+                    "versions.yml:md5,832e36b56615fb29a94b16e4db32b8db"
+                ],
+                "dupfile": [
+                    
+                ],
+                "log": [
+                    
+                ],
+                "markduped": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.bam:md5,86e22a794d904cc48cb3758a03883ba1"
+                    ]
+                ],
+                "versions": [
+                    "versions.yml:md5,832e36b56615fb29a94b16e4db32b8db"
+                ]
+            }
+        ],
+        "meta": {
+            "nf-test": "0.9.2",
+            "nextflow": "25.04.2"
+        },
+        "timestamp": "2025-11-27T22:25:53.428359"
+    },
+    "acropora cervicornis - bam - multiple tests with dupfile and log": {
+        "content": [
+            {
+                "0": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.bam:md5,86e22a794d904cc48cb3758a03883ba1"
+                    ]
+                ],
+                "1": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "null.dup.bam:md5,3b74225ad5f7e9e1cbafc45132ad82fb"
+                    ]
+                ],
+                "2": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.pbmarkdup.log:md5,99987a1331d01b59aa3b5ccd1c787906"
+                    ]
+                ],
+                "3": [
+                    "versions.yml:md5,832e36b56615fb29a94b16e4db32b8db"
+                ],
+                "dupfile": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "null.dup.bam:md5,3b74225ad5f7e9e1cbafc45132ad82fb"
+                    ]
+                ],
+                "log": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.pbmarkdup.log:md5,99987a1331d01b59aa3b5ccd1c787906"
+                    ]
+                ],
+                "markduped": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.bam:md5,86e22a794d904cc48cb3758a03883ba1"
+                    ]
+                ],
+                "versions": [
+                    "versions.yml:md5,832e36b56615fb29a94b16e4db32b8db"
+                ]
+            }
+        ],
+        "meta": {
+            "nf-test": "0.9.2",
+            "nextflow": "25.04.2"
+        },
+        "timestamp": "2025-11-27T22:25:23.374664"
+    },
+    "deilephila porcellus - stub": {
+        "content": [
+            {
+                "0": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.fa:md5,d41d8cd98f00b204e9800998ecf8427e"
+                    ]
+                ],
+                "1": [
+                    
+                ],
+                "2": [
+                    
+                ],
+                "3": [
+                    "versions.yml:md5,832e36b56615fb29a94b16e4db32b8db"
+                ],
+                "dupfile": [
+                    
+                ],
+                "log": [
+                    
+                ],
+                "markduped": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.fa:md5,d41d8cd98f00b204e9800998ecf8427e"
+                    ]
+                ],
+                "versions": [
+                    "versions.yml:md5,832e36b56615fb29a94b16e4db32b8db"
+                ]
+            }
+        ],
+        "meta": {
+            "nf-test": "0.9.2",
+            "nextflow": "25.04.2"
+        },
+        "timestamp": "2025-11-27T22:26:16.491708"
+    },
+    "deilephila porcellus - fasta": {
+        "content": [
+            {
+                "0": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.fa:md5,087cee5291f8d728a62b91765b64af35"
+                    ]
+                ],
+                "1": [
+                    
+                ],
+                "2": [
+                    
+                ],
+                "3": [
+                    "versions.yml:md5,832e36b56615fb29a94b16e4db32b8db"
+                ],
+                "dupfile": [
+                    
+                ],
+                "log": [
+                    
+                ],
+                "markduped": [
+                    [
+                        {
+                            "id": "test"
+                        },
+                        "test.fa:md5,087cee5291f8d728a62b91765b64af35"
+                    ]
+                ],
+                "versions": [
+                    "versions.yml:md5,832e36b56615fb29a94b16e4db32b8db"
+                ]
+            }
+        ],
+        "meta": {
+            "nf-test": "0.9.2",
+            "nextflow": "25.04.2"
+        },
+        "timestamp": "2025-11-27T22:47:33.595865"
+    }
+}
\ No newline at end of file
diff --git a/modules/nf-core/pbmarkdup/tests/nextflow.config b/modules/nf-core/pbmarkdup/tests/nextflow.config
new file mode 100644
index 00000000000..dc9b092f013
--- /dev/null
+++ b/modules/nf-core/pbmarkdup/tests/nextflow.config
@@ -0,0 +1,5 @@
+process {
+    withName: PBMARKDUP {
+        ext.args = { "${params.pbmarkdup_args}" }
+    }
+}