diff --git a/change/@fluentui-react-tree-9ce25cd9-37b5-4f07-8832-c69f0b2667b7.json b/change/@fluentui-react-tree-9ce25cd9-37b5-4f07-8832-c69f0b2667b7.json
new file mode 100644
index 00000000000000..04645be8cf9eff
--- /dev/null
+++ b/change/@fluentui-react-tree-9ce25cd9-37b5-4f07-8832-c69f0b2667b7.json
@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "chore: deprecate flattenTree",
+  "packageName": "@fluentui/react-tree",
+  "email": "bernardo.sunderhus@gmail.com",
+  "dependentChangeType": "patch"
+}
diff --git a/packages/react-components/react-tree/library/etc/react-tree.api.md b/packages/react-components/react-tree/library/etc/react-tree.api.md
index 210a53b0625064..88f3521446357f 100644
--- a/packages/react-components/react-tree/library/etc/react-tree.api.md
+++ b/packages/react-components/react-tree/library/etc/react-tree.api.md
@@ -34,10 +34,10 @@ import type { SelectionMode as SelectionMode_2 } from '@fluentui/react-utilities
 import type { Slot } from '@fluentui/react-utilities';
 import type { SlotClassNames } from '@fluentui/react-utilities';
 
-// @public
+// @public @deprecated (undocumented)
 export const flattenTree_unstable: <Props extends TreeItemProps>(items: FlattenTreeItem<Props>[]) => FlattenedTreeItem<Props>[];
 
-// @public (undocumented)
+// @public @deprecated (undocumented)
 export type FlattenTreeItem<Props extends TreeItemProps> = Omit<Props, 'subtree' | 'itemType'> & {
     value: TreeItemValue;
     subtree?: FlattenTreeItem<Props>[];
diff --git a/packages/react-components/react-tree/library/src/utils/flattenTree.ts b/packages/react-components/react-tree/library/src/utils/flattenTree.ts
index 5812f933601804..84abc37f68238f 100644
--- a/packages/react-components/react-tree/library/src/utils/flattenTree.ts
+++ b/packages/react-components/react-tree/library/src/utils/flattenTree.ts
@@ -1,18 +1,27 @@
 import { HeadlessFlatTreeItemProps } from '../FlatTree';
 import { TreeItemProps, TreeItemValue } from '../TreeItem';
 
+/**
+ * @deprecated - deprecating in favor of user flattening its custom data structure on its own
+ */
 export type FlattenTreeItem<Props extends TreeItemProps> = Omit<Props, 'subtree' | 'itemType'> & {
   value: TreeItemValue;
   subtree?: FlattenTreeItem<Props>[];
 };
 
+/**
+ * @deprecated - deprecating in favor of user flattening its custom data structure on its own
+ */
 export type FlattenedTreeItem<Props extends TreeItemProps> = HeadlessFlatTreeItemProps & Props;
 
 function flattenTreeRecursive<Props extends TreeItemProps>(
+  // eslint-disable-next-line @typescript-eslint/no-deprecated
   items: FlattenTreeItem<Props>[],
   parent?: HeadlessFlatTreeItemProps & Props,
   level = 1,
+  // eslint-disable-next-line @typescript-eslint/no-deprecated
 ): FlattenedTreeItem<Props>[] {
+  // eslint-disable-next-line @typescript-eslint/no-deprecated
   return items.reduce<FlattenedTreeItem<Props>[]>((acc, { subtree, ...item }, index) => {
     const flatTreeItem = {
       'aria-level': level,
@@ -20,6 +29,7 @@ function flattenTreeRecursive<Props extends TreeItemProps>(
       'aria-setsize': items.length,
       parentValue: parent?.value,
       ...item,
+      // eslint-disable-next-line @typescript-eslint/no-deprecated
     } as FlattenedTreeItem<Props>;
     acc.push(flatTreeItem);
     if (subtree !== undefined) {
@@ -30,6 +40,9 @@ function flattenTreeRecursive<Props extends TreeItemProps>(
 }
 
 /**
+ *
+ * @deprecated - deprecating in favor of user flattening its custom data structure on its own
+ *
  * Converts a nested structure to a flat one which can be consumed by `useFlatTreeItems`
  * @example
  * ```tsx
@@ -71,5 +84,7 @@ function flattenTreeRecursive<Props extends TreeItemProps>(
  */
 // eslint-disable-next-line @typescript-eslint/naming-convention
 export const flattenTree_unstable = <Props extends TreeItemProps>(
+  // eslint-disable-next-line @typescript-eslint/no-deprecated
   items: FlattenTreeItem<Props>[],
+  // eslint-disable-next-line @typescript-eslint/no-deprecated
 ): FlattenedTreeItem<Props>[] => flattenTreeRecursive(items);
diff --git a/packages/react-components/react-tree/stories/src/Tree/UseHeadlessFlatTree.stories.tsx b/packages/react-components/react-tree/stories/src/Tree/UseHeadlessFlatTree.stories.tsx
index d30f4e6b0ecf73..c24cd5a5f68089 100644
--- a/packages/react-components/react-tree/stories/src/Tree/UseHeadlessFlatTree.stories.tsx
+++ b/packages/react-components/react-tree/stories/src/Tree/UseHeadlessFlatTree.stories.tsx
@@ -32,54 +32,6 @@ const flatTreeItems: FlatItem[] = [
   { value: '2-1-1-1', parentValue: '2-1-1', content: 'Level 4, item 1' },
 ];
 
-// // EXAMPLE OF NESTED TREE ITEMS BEING FLATTEN BY `flattenTree`:
-// type Item = TreeItemProps & { content: React.ReactNode };
-
-// const nestedTreeItems = [
-//   {
-//     value: '1',
-//     content: <>level 1, item 1</>,
-//     subtree: [
-//       {
-//         value: '1-1',
-//         content: <>level 2, item 1</>,
-//       },
-//       {
-//         value: '1-2',
-//         content: <>level 2, item 2</>,
-//       },
-//       {
-//         value: '1-3',
-//         content: <>level 2, item 3</>,
-//       },
-//     ],
-//   },
-//   {
-//     value: '2',
-//     content: <>level 1, item 2</>,
-//     subtree: [
-//       {
-//         value: '2-1',
-//         content: <>level 2, item 1</>,
-//         subtree: [
-//           {
-//             value: '2-1-1',
-//             content: <>level 3, item 1</>,
-//             subtree: [
-//               {
-//                 value: '2-1-1-1',
-//                 content: <>level 4, item 1</>,
-//               },
-//             ],
-//           },
-//         ],
-//       },
-//     ],
-//   },
-// ];
-
-// const flatTreeItems = flattenTree_unstable<Item>(nestedTreeItems);
-
 const ActionsExample = () => (
   <>
     <Button aria-label="Edit" appearance="subtle" icon={<Edit20Regular />} />
diff --git a/packages/react-components/react-tree/stories/src/Tree/UseHeadlessFlatTreeWithNestedStructure.stories.tsx b/packages/react-components/react-tree/stories/src/Tree/UseHeadlessFlatTreeWithNestedStructure.stories.tsx
new file mode 100644
index 00000000000000..f12a895cba0b06
--- /dev/null
+++ b/packages/react-components/react-tree/stories/src/Tree/UseHeadlessFlatTreeWithNestedStructure.stories.tsx
@@ -0,0 +1,84 @@
+import * as React from 'react';
+import {
+  FlatTree,
+  TreeItem,
+  TreeItemLayout,
+  useHeadlessFlatTree_unstable,
+  HeadlessFlatTreeItemProps,
+  TreeItemValue,
+} from '@fluentui/react-components';
+
+type FlatTreeItem = HeadlessFlatTreeItemProps & { content: React.ReactNode };
+type NestedTreeItem = FlatTreeItem & { subtree?: NestedTreeItem[] };
+
+const flattenTree = (items: NestedTreeItem[], parentValue?: TreeItemValue | undefined): FlatTreeItem[] =>
+  items.flatMap<FlatTreeItem>(({ subtree, ...item }) =>
+    subtree ? [{ ...item, parentValue }, ...flattenTree(subtree, item.value)] : { parentValue, ...item },
+  );
+
+const flatTreeItems = flattenTree([
+  {
+    value: '1',
+    content: <>level 1, item 1</>,
+    subtree: [
+      {
+        value: '1-1',
+        content: <>level 2, item 1</>,
+      },
+      {
+        value: '1-2',
+        content: <>level 2, item 2</>,
+      },
+      {
+        value: '1-3',
+        content: <>level 2, item 3</>,
+      },
+    ],
+  },
+  {
+    value: '2',
+    content: <>level 1, item 2</>,
+    subtree: [
+      {
+        value: '2-1',
+        content: <>level 2, item 1</>,
+        subtree: [
+          {
+            value: '2-1-1',
+            content: <>level 3, item 1</>,
+            subtree: [
+              {
+                value: '2-1-1-1',
+                content: <>level 4, item 1</>,
+              },
+            ],
+          },
+        ],
+      },
+    ],
+  },
+]);
+
+export const UseHeadlessFlatTreeWithNestedStructure = () => {
+  const flatTree = useHeadlessFlatTree_unstable(flatTreeItems);
+  return (
+    <FlatTree {...flatTree.getTreeProps()} aria-label="Flat Tree">
+      {Array.from(flatTree.items(), flatTreeItem => {
+        const { content, ...treeItemProps } = flatTreeItem.getTreeItemProps();
+        return (
+          <TreeItem key={treeItemProps.value} {...treeItemProps}>
+            <TreeItemLayout>{content}</TreeItemLayout>
+          </TreeItem>
+        );
+      })}
+    </FlatTree>
+  );
+};
+
+UseHeadlessFlatTreeWithNestedStructure.parameters = {
+  docs: {
+    description: {
+      story: `If your data structure is nested, it can be converted to a flat structure before providing it to \`useHeadlessFlatTree\`. Here's an example using recursion and [\`Array.flatMap\`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/flatMap) to convert a nested array of items (nested by the property \`subtree\`) into a flat array of items:`,
+    },
+  },
+};
diff --git a/packages/react-components/react-tree/stories/src/Tree/index.stories.tsx b/packages/react-components/react-tree/stories/src/Tree/index.stories.tsx
index cfbc1e6fd3973e..b98c019009fab4 100644
--- a/packages/react-components/react-tree/stories/src/Tree/index.stories.tsx
+++ b/packages/react-components/react-tree/stories/src/Tree/index.stories.tsx
@@ -32,6 +32,7 @@ export { FlatTreeStory as FlatTree } from './FlatTree.stories';
 
 // SCENARIOS & FEATURES
 export { UseHeadlessFlatTree } from './UseHeadlessFlatTree.stories';
+export { UseHeadlessFlatTreeWithNestedStructure } from './UseHeadlessFlatTreeWithNestedStructure.stories';
 export { Selection } from './TreeSelection.stories';
 export { Manipulation } from './TreeManipulation.stories';
 export { LazyLoading } from './TreeLazyLoading.stories';