diff --git a/examples/vue-custom-mark/src/App.vue b/examples/vue-custom-mark/src/App.vue
index d9ad688dd9..8299820cb8 100644
--- a/examples/vue-custom-mark/src/App.vue
+++ b/examples/vue-custom-mark/src/App.vue
@@ -20,7 +20,6 @@ const init = () => {
     editorExtensions: [CustomMark],
     onReady: myCustomOnReady,
   });
-
 };
 
 
@@ -53,6 +52,12 @@ const insertCustomMark = () => {
   superdoc.value?.activeEditor?.commands.setMyCustomMark(randomId);
 };
 
+const exportDocx = () => {
+  superdoc.value?.export({
+    exportType: ['docx']
+  });
+};
+
 onMounted(() => init());
 </script>
 
@@ -65,8 +70,9 @@ onMounted(() => init());
     <div id="toolbar" class="my-custom-toolbar"></div>
     <div class="editor-and-button">
       <div id="editor" class="main-editor"></div>
-      <div>
+      <div class="editor-buttons">
         <button class="insert-mark" @click="insertCustomMark">Insert custom mark</button>
+        <button class="insert-mark" @click="exportDocx">Export</button>
       </div>
     </div>
   </div>
@@ -85,6 +91,13 @@ onMounted(() => init());
   align-items: flex-start;
   justify-content: center;
 }
+.editor-buttons {
+  display: flex;
+  flex-direction: column;
+}
+.editor-buttons button {
+  margin-bottom: 10px;
+}
 .insert-mark {
   padding: 8px 12px;
   border-radius: 8px;
diff --git a/packages/super-editor/src/core/Editor.js b/packages/super-editor/src/core/Editor.js
index 0c008bfd4b..e9a976e217 100644
--- a/packages/super-editor/src/core/Editor.js
+++ b/packages/super-editor/src/core/Editor.js
@@ -1013,6 +1013,7 @@ export class Editor extends EventEmitter {
       isFinalDoc,
       commentsType,
       comments,
+      this,
     );
 
     const customXml = this.converter.schemaToXml(this.converter.convertedXml['docProps/custom.xml'].elements[0]);
diff --git a/packages/super-editor/src/core/ExtensionService.js b/packages/super-editor/src/core/ExtensionService.js
index 271d8f595d..a7f93312fc 100644
--- a/packages/super-editor/src/core/ExtensionService.js
+++ b/packages/super-editor/src/core/ExtensionService.js
@@ -26,6 +26,14 @@ export class ExtensionService {
     this.editor = editor;
 
     this.externalExtensions = userExtensions || [];
+
+    this.externalExtensions = this.externalExtensions.map((extension) => {
+      return {
+        ...extension,
+        isExternal: true,
+      };
+    });
+  
     this.extensions = ExtensionService.getResolvedExtensions([...extensions, ...this.externalExtensions]);
     this.schema = Schema.createSchemaByExtensions(this.extensions, editor);
     this.#setupExtensions();
diff --git a/packages/super-editor/src/core/Mark.js b/packages/super-editor/src/core/Mark.js
index 04ecdd2918..388ba7fc40 100644
--- a/packages/super-editor/src/core/Mark.js
+++ b/packages/super-editor/src/core/Mark.js
@@ -13,6 +13,8 @@ export class Mark {
 
   storage;
 
+  isExternal;
+
   config = {
     name: this.name,
   };
@@ -25,6 +27,8 @@ export class Mark {
 
     this.name = this.config.name;
 
+    this.isExternal = Boolean(this.config.isExternal)
+
     if (this.config.addOptions) {
       this.options = callOrGet(
         getExtensionConfigField(this, 'addOptions', {
diff --git a/packages/super-editor/src/core/super-converter/SuperConverter.js b/packages/super-editor/src/core/super-converter/SuperConverter.js
index 91f544b630..3146373f3b 100644
--- a/packages/super-editor/src/core/super-converter/SuperConverter.js
+++ b/packages/super-editor/src/core/super-converter/SuperConverter.js
@@ -321,6 +321,7 @@ class SuperConverter {
     isFinalDoc = false,
     commentsExportType,
     comments = [],
+    editor,
   ) {
     const commentsWithParaIds = comments.map((c) => prepareCommentParaIds(c));
     const commentDefinitions = commentsWithParaIds
@@ -332,7 +333,8 @@ class SuperConverter {
       comments,
       commentDefinitions,
       commentsExportType,
-      isFinalDoc
+      isFinalDoc,
+      editor,
     });
 
     const exporter = new DocxExporter(this);
@@ -378,7 +380,8 @@ class SuperConverter {
     comments,
     commentDefinitions,
     commentsExportType = 'clean',
-    isFinalDoc = false
+    isFinalDoc = false,
+    editor,
   }) {
     const bodyNode = this.savedTagsToRestore.find((el) => el.name === 'w:body');
 
@@ -395,6 +398,7 @@ class SuperConverter {
       comments,
       commentsExportType,
       exportedCommentDefs: commentDefinitions,
+      editor,
     });
 
     return { result, params };
diff --git a/packages/super-editor/src/core/super-converter/exporter.js b/packages/super-editor/src/core/super-converter/exporter.js
index 7a98d78aa3..bb2a92e128 100644
--- a/packages/super-editor/src/core/super-converter/exporter.js
+++ b/packages/super-editor/src/core/super-converter/exporter.js
@@ -344,19 +344,61 @@ function translateChildNodes(params) {
  * @returns {XmlReadyNode} The translated text node
  */
 
-function getTextNodeForExport(text, marks) {
+function getTextNodeForExport(text, marks, params) {
   const hasLeadingOrTrailingSpace = /^\s|\s$/.test(text);
   const space = hasLeadingOrTrailingSpace ? 'preserve' : null;
   const nodeAttrs = space ? { 'xml:space': space } : null;
-  
+  const textNodes = [];
+
   const outputMarks = processOutputMarks(marks);
-  const textNode = {
+  textNodes.push({
     name: 'w:t',
     elements: [{ text, type: 'text' }],
     attributes: nodeAttrs,
-  };
+  });
+
+  // For custom mark export, we need to add a bookmark start and end tag
+  // And store attributes in the bookmark name
+  if (params) {
+    const { editor } = params;
+    const customMarks = editor.extensionService.extensions.filter((e) => e.isExternal === true);
+
+    marks.forEach((mark) => {
+      const isCustomMark = customMarks.some((customMark) => {
+        const customMarkName = customMark.name;
+        return mark.type === customMarkName;
+      });
+
+      if (!isCustomMark) return;
   
-  return wrapTextInRun(textNode, outputMarks);
+      let attrsString = '';
+      Object.entries(mark.attrs).forEach(([key, value]) => {
+        if (value) {
+          attrsString += `${key}=${value};`;
+        }
+      }); 
+
+      if (isCustomMark) {
+        textNodes.unshift({
+          type: 'element',
+          name: 'w:bookmarkStart',
+          attributes: {
+            'w:id': '5000',
+            'w:name': mark.type + ';' + attrsString,
+          }
+        });
+        textNodes.push({
+          type: 'element',
+          name: 'w:bookmarkEnd',
+          attributes: {
+            'w:id': '5000',
+          }
+        });
+      };
+    });
+  }
+
+  return wrapTextInRun(textNodes, outputMarks);
 }
 
 /**
@@ -383,7 +425,7 @@ function translateTextNode(params) {
 
   const { text, marks = [] } = node;
 
-  return getTextNodeForExport(text, marks);
+  return getTextNodeForExport(text, marks, params);
 }
 
 function createTrackStyleMark(marks) {
@@ -448,8 +490,11 @@ function translateTrackedNode(params) {
  * @param {XmlReadyNode} node
  * @returns {XmlReadyNode} The wrapped run node
  */
-function wrapTextInRun(node, marks) {
-  const elements = [node];
+function wrapTextInRun(nodeOrNodes, marks) {
+  let elements = [];
+  if (Array.isArray(nodeOrNodes)) elements = nodeOrNodes;
+  else elements = [nodeOrNodes];
+
   if (marks && marks.length) elements.unshift(generateRunProps(marks));
   return {
     name: 'w:r',
@@ -1546,7 +1591,7 @@ function prepareTextAnnotation(params) {
   } = params;
 
   const marksFromAttrs = translateFieldAttrsToMarks(attrs);
-  return getTextNodeForExport(attrs.displayLabel, [...marks, ...marksFromAttrs]);
+  return getTextNodeForExport(attrs.displayLabel, [...marks, ...marksFromAttrs], params);
 }
 
 /**
@@ -1560,7 +1605,7 @@ function prepareCheckboxAnnotation(params) {
     node: { attrs = {}, marks = [] },
   } = params;
   const content = he.decode(attrs.displayLabel);
-  return getTextNodeForExport(content, marks);
+  return getTextNodeForExport(content, marks, params);
 }
 
 /**
@@ -1613,7 +1658,7 @@ function prepareUrlAnnotation(params) {
   } = params;
   const newId = addNewLinkRelationship(params, attrs.linkUrl);
 
-  const linkTextNode = getTextNodeForExport(attrs.linkUrl, marks);
+  const linkTextNode = getTextNodeForExport(attrs.linkUrl, marks, params);
 
   return {
     name: 'w:hyperlink',
diff --git a/packages/super-editor/src/core/super-converter/v2/importer/bookmarkNodeImporter.js b/packages/super-editor/src/core/super-converter/v2/importer/bookmarkNodeImporter.js
index 9d9e2a27bb..997cc5ca75 100644
--- a/packages/super-editor/src/core/super-converter/v2/importer/bookmarkNodeImporter.js
+++ b/packages/super-editor/src/core/super-converter/v2/importer/bookmarkNodeImporter.js
@@ -2,12 +2,11 @@
  * @type {import("docxImporter").NodeHandler}
  */
 export const handleBookmarkNode = (params) => {
-  const { nodes, nodeListHandler } = params;
+  const { nodes, nodeListHandler, editor } = params;
   if (nodes.length === 0 || nodes[0].name !== 'w:bookmarkStart') {
     return { nodes: [], consumed: 0 };
   }
   const node = nodes[0];
-
   const handleStandardNode = nodeListHandler.handlerEntities.find(
     (e) => e.handlerName === 'standardNodeHandler',
   )?.handler;
@@ -16,6 +15,36 @@ export const handleBookmarkNode = (params) => {
     return { nodes: [], consumed: 0 };
   };
 
+  // Check if this bookmark is a custom mark
+  const customMarks = editor?.extensionService?.extensions?.filter((e) => e.isExternal === true) || [];
+  const bookmarkName = node.attributes['w:name']?.split(';')[0];
+  const customMark = customMarks.find((mark) => mark.name === bookmarkName);
+  if (customMark) {
+    const bookmarkEndIndex = nodes.findIndex((n) => n.name === 'w:bookmarkEnd' && n.attributes['w:id'] === node.attributes['w:id']);
+    const textNodes = nodes.slice(1, bookmarkEndIndex);
+
+    const nodeListHandler = params.nodeListHandler;
+    const attrs = {};
+    node.attributes['w:name'].split(';').forEach((name) => {
+      const [key, value] = name.split('=');
+      if (key && value) {
+        attrs[key] = value;
+      }
+    });
+  
+    const translatedText = nodeListHandler.handler({ ...params, nodes: textNodes });
+    translatedText.forEach((n) => {
+      n.marks.push({
+        type: customMark.name,
+        attrs,
+      })
+    });
+    return {
+      nodes: translatedText,
+      consumed: translatedText.length + 2,
+    };
+  }
+
   const updatedParams = {...params, nodes: [node]};
   const result = handleStandardNode(updatedParams);
   if (result.nodes.length === 1) {
diff --git a/packages/super-editor/src/core/super-converter/v2/importer/runNodeImporter.js b/packages/super-editor/src/core/super-converter/v2/importer/runNodeImporter.js
index f3412a8157..53ce565938 100644
--- a/packages/super-editor/src/core/super-converter/v2/importer/runNodeImporter.js
+++ b/packages/super-editor/src/core/super-converter/v2/importer/runNodeImporter.js
@@ -26,7 +26,11 @@ const handleRunNode = (params) => {
     }
     
     if (node.marks) marks.push(...node.marks);
-    processedRun = processedRun.map((n) => ({ ...n, marks: createImportMarks(marks), attributes }));
+    const newMarks = createImportMarks(marks);
+    processedRun = processedRun.map((n) => { 
+      const existingMarks = n.marks || [];
+      return { ...n, marks: [...newMarks, ...existingMarks], attributes }
+    });
   } else if (defaultNodeStyles.marks) {
     processedRun = processedRun.map((n) => ({ ...n, marks: createImportMarks(defaultNodeStyles.marks) }));
   }