diff --git a/change/@fluentui-react-tabster-8a739d1e-a76c-4604-90e3-5ddb2d3da5fa.json b/change/@fluentui-react-tabster-8a739d1e-a76c-4604-90e3-5ddb2d3da5fa.json
new file mode 100644
index 00000000000000..e7fd20458e4791
--- /dev/null
+++ b/change/@fluentui-react-tabster-8a739d1e-a76c-4604-90e3-5ddb2d3da5fa.json
@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "feat: add `unstable_hasDefault` option in `useArrowNavigationGroup` that specifies the arrow navigation group has default focusable item",
+  "packageName": "@fluentui/react-tabster",
+  "email": "yuanboxue@microsoft.com",
+  "dependentChangeType": "patch"
+}
diff --git a/packages/react-components/react-tabster/etc/react-tabster.api.md b/packages/react-components/react-tabster/etc/react-tabster.api.md
index a6063a42a23c05..e7a5482fe9ed45 100644
--- a/packages/react-components/react-tabster/etc/react-tabster.api.md
+++ b/packages/react-components/react-tabster/etc/react-tabster.api.md
@@ -53,6 +53,7 @@ export interface UseArrowNavigationGroupOptions {
     ignoreDefaultKeydown?: Types.FocusableProps['ignoreKeydown'];
     memorizeCurrent?: boolean;
     tabbable?: boolean;
+    unstable_hasDefault?: boolean;
 }
 
 // @public
diff --git a/packages/react-components/react-tabster/src/hooks/useArrowNavigationGroup.ts b/packages/react-components/react-tabster/src/hooks/useArrowNavigationGroup.ts
index 993b86f2427303..f9aca20f45e4af 100644
--- a/packages/react-components/react-tabster/src/hooks/useArrowNavigationGroup.ts
+++ b/packages/react-components/react-tabster/src/hooks/useArrowNavigationGroup.ts
@@ -25,6 +25,13 @@ export interface UseArrowNavigationGroupOptions {
    * Tabster should ignore default handling of keydown events
    */
   ignoreDefaultKeydown?: Types.FocusableProps['ignoreKeydown'];
+  /**
+   * The default focusable item in the group will be an element with Focusable.isDefault property.
+   * Note that there is no way in \@fluentui/react-tabster to set default focusable element,
+   * and this option is currently for internal testing purposes only.
+   */
+  // eslint-disable-next-line @typescript-eslint/naming-convention
+  unstable_hasDefault?: boolean;
 }
 
 /**
@@ -32,7 +39,15 @@ export interface UseArrowNavigationGroupOptions {
  * @param options - Options to configure keyboard navigation
  */
 export const useArrowNavigationGroup = (options: UseArrowNavigationGroupOptions = {}): Types.TabsterDOMAttribute => {
-  const { circular, axis, memorizeCurrent, tabbable, ignoreDefaultKeydown } = options;
+  const {
+    circular,
+    axis,
+    memorizeCurrent,
+    tabbable,
+    ignoreDefaultKeydown,
+    // eslint-disable-next-line @typescript-eslint/naming-convention
+    unstable_hasDefault,
+  } = options;
   const tabster = useTabster();
 
   if (tabster) {
@@ -43,8 +58,9 @@ export const useArrowNavigationGroup = (options: UseArrowNavigationGroupOptions
     mover: {
       cyclic: !!circular,
       direction: axisToMoverDirection(axis ?? 'vertical'),
-      memorizeCurrent: memorizeCurrent,
-      tabbable: tabbable,
+      memorizeCurrent,
+      tabbable,
+      hasDefault: unstable_hasDefault,
     },
     ...(ignoreDefaultKeydown && {
       focusable: {