diff --git a/libraries/common/src/main/java/androidx/media3/common/text/CustomSpanBundler.java b/libraries/common/src/main/java/androidx/media3/common/text/CustomSpanBundler.java
index edcda586d2d..0734e684993 100644
--- a/libraries/common/src/main/java/androidx/media3/common/text/CustomSpanBundler.java
+++ b/libraries/common/src/main/java/androidx/media3/common/text/CustomSpanBundler.java
@@ -53,12 +53,13 @@
    *   <li>{@link #RUBY}
    *   <li>{@link #TEXT_EMPHASIS}
    *   <li>{@link #HORIZONTAL_TEXT_IN_VERTICAL_CONTEXT}
+   *   <li>{@link #OUTLINE_WIDTH}
    * </ul>
    */
   @Documented
   @Retention(RetentionPolicy.SOURCE)
   @Target({TYPE_USE})
-  @IntDef({UNKNOWN, RUBY, TEXT_EMPHASIS, HORIZONTAL_TEXT_IN_VERTICAL_CONTEXT})
+  @IntDef({UNKNOWN, RUBY, TEXT_EMPHASIS, HORIZONTAL_TEXT_IN_VERTICAL_CONTEXT, OUTLINE_WIDTH})
   private @interface CustomSpanType {}
 
   private static final int UNKNOWN = -1;
@@ -69,6 +70,8 @@
 
   private static final int HORIZONTAL_TEXT_IN_VERTICAL_CONTEXT = 3;
 
+  private static final int OUTLINE_WIDTH = 4;
+
   private static final String FIELD_START_INDEX = Util.intToStringMaxRadix(0);
   private static final String FIELD_END_INDEX = Util.intToStringMaxRadix(1);
   private static final String FIELD_FLAGS = Util.intToStringMaxRadix(2);
@@ -94,6 +97,11 @@ public static ArrayList<Bundle> bundleCustomSpans(Spanned text) {
               text, span, /* spanType= */ HORIZONTAL_TEXT_IN_VERTICAL_CONTEXT, /* params= */ null);
       bundledCustomSpans.add(bundle);
     }
+    for (OutlineSpan span : text.getSpans(0, text.length(), OutlineSpan.class)) {
+      Bundle bundle =
+          spanToBundle(text, span, /* spanType= */ OUTLINE_WIDTH, /* params= */ span.toBundle());
+      bundledCustomSpans.add(bundle);
+    }
     return bundledCustomSpans;
   }
 
@@ -113,6 +121,8 @@ public static void unbundleAndApplyCustomSpan(Bundle customSpanBundle, Spannable
       case HORIZONTAL_TEXT_IN_VERTICAL_CONTEXT:
         text.setSpan(new HorizontalTextInVerticalContextSpan(), start, end, flags);
         break;
+      case OUTLINE_WIDTH:
+        text.setSpan(OutlineSpan.fromBundle(checkNotNull(span)),start,end,flags);
       default:
         break;
     }
diff --git a/libraries/common/src/main/java/androidx/media3/common/text/OutlineSpan.java b/libraries/common/src/main/java/androidx/media3/common/text/OutlineSpan.java
new file mode 100644
index 00000000000..a9afd4ffd8f
--- /dev/null
+++ b/libraries/common/src/main/java/androidx/media3/common/text/OutlineSpan.java
@@ -0,0 +1,41 @@
+package androidx.media3.common.text;
+
+import android.os.Bundle;
+import android.text.TextPaint;
+import android.text.style.CharacterStyle;
+import androidx.annotation.Px;
+import androidx.media3.common.util.Util;
+
+/**
+ * A styling span for outline width on subtitle text.
+ */
+public class OutlineSpan extends CharacterStyle {
+
+  /**
+   * The outline size in pixels.
+   */
+  @Px
+  public final float outlineWidth;
+  private static final String FIELD_OUTLINE_WIDTH = Util.intToStringMaxRadix(0);
+
+  public OutlineSpan(@Px float outlineWidth) {
+    this.outlineWidth = outlineWidth;
+  }
+
+  public Bundle toBundle() {
+    Bundle bundle = new Bundle();
+    bundle.putFloat(FIELD_OUTLINE_WIDTH, outlineWidth);
+    return bundle;
+  }
+
+  public static OutlineSpan fromBundle(Bundle bundle) {
+    return new OutlineSpan(
+        /* outlineWidth= */ bundle.getFloat(FIELD_OUTLINE_WIDTH)
+    );
+  }
+
+  @Override
+  public void updateDrawState(TextPaint tp) {
+    tp.setStrokeWidth(outlineWidth);
+  }
+}
diff --git a/libraries/ui/src/main/java/androidx/media3/ui/SpannedToHtmlConverter.java b/libraries/ui/src/main/java/androidx/media3/ui/SpannedToHtmlConverter.java
index 930579f78c0..de56631b9b1 100644
--- a/libraries/ui/src/main/java/androidx/media3/ui/SpannedToHtmlConverter.java
+++ b/libraries/ui/src/main/java/androidx/media3/ui/SpannedToHtmlConverter.java
@@ -30,6 +30,7 @@
 import android.util.SparseArray;
 import androidx.annotation.Nullable;
 import androidx.media3.common.text.HorizontalTextInVerticalContextSpan;
+import androidx.media3.common.text.OutlineSpan;
 import androidx.media3.common.text.RubySpan;
 import androidx.media3.common.text.TextAnnotation;
 import androidx.media3.common.text.TextEmphasisSpan;
@@ -207,6 +208,12 @@ private static String getOpeningTag(Object span, float displayDensity) {
               + "-webkit-text-emphasis-position:%2$s;text-emphasis-position:%2$s;"
               + "display:inline-block;'>",
           style, position);
+    } else if (span instanceof OutlineSpan) {
+        OutlineSpan outline = ((OutlineSpan) span);
+        return Util.formatInvariant(
+            "<span style='-webkit-text-stroke-width: %1$spx;'>",
+            outline.outlineWidth
+        );
     } else {
       return null;
     }
@@ -220,7 +227,8 @@ private static String getClosingTag(Object span) {
         || span instanceof HorizontalTextInVerticalContextSpan
         || span instanceof AbsoluteSizeSpan
         || span instanceof RelativeSizeSpan
-        || span instanceof TextEmphasisSpan) {
+        || span instanceof TextEmphasisSpan
+        || span instanceof OutlineSpan) {
       return "</span>";
     } else if (span instanceof TypefaceSpan) {
       @Nullable String fontFamily = ((TypefaceSpan) span).getFamily();
diff --git a/libraries/ui/src/main/java/androidx/media3/ui/WebViewSubtitleOutput.java b/libraries/ui/src/main/java/androidx/media3/ui/WebViewSubtitleOutput.java
index d1ee761e47e..e589cc18237 100644
--- a/libraries/ui/src/main/java/androidx/media3/ui/WebViewSubtitleOutput.java
+++ b/libraries/ui/src/main/java/androidx/media3/ui/WebViewSubtitleOutput.java
@@ -177,11 +177,13 @@ private void updateWebView() {
                 + "font-size:%s;"
                 + "line-height:%.2f;"
                 + "text-shadow:%s;"
+                + "-webkit-text-stroke-color: %s;"
                 + "'>",
             HtmlUtils.toCssRgba(style.foregroundColor),
             convertTextSizeToCss(defaultTextSizeType, defaultTextSize),
             CSS_LINE_HEIGHT,
-            convertCaptionStyleToCssTextShadow(style)));
+            convertCaptionStyleToCssTextShadow(style),
+            HtmlUtils.toCssRgba(style.edgeColor)));
 
     Map<String, String> cssRuleSets = new HashMap<>();
     cssRuleSets.put(