diff --git a/.changeset/fix-basename-duplication.md b/.changeset/fix-basename-duplication.md
new file mode 100644
index 0000000000..13c1963ed1
--- /dev/null
+++ b/.changeset/fix-basename-duplication.md
@@ -0,0 +1,5 @@
+---
+"react-router": patch
+---
+
+Fix `basename` duplication in descenant `<Routes>` inside a `<RouterProvider>`
diff --git a/packages/react-router/__tests__/useNavigate-test.tsx b/packages/react-router/__tests__/useNavigate-test.tsx
index 3e3dead5b4..4512c03c5f 100644
--- a/packages/react-router/__tests__/useNavigate-test.tsx
+++ b/packages/react-router/__tests__/useNavigate-test.tsx
@@ -2053,6 +2053,181 @@ describe("useNavigate", () => {
       `);
     });
   });
+
+  describe("with a basename", () => {
+    describe("in a MemoryRouter", () => {
+      it("in a root route", () => {
+        let renderer: TestRenderer.ReactTestRenderer;
+        TestRenderer.act(() => {
+          renderer = TestRenderer.create(
+            <MemoryRouter basename="/base" initialEntries={["/base"]}>
+              <Routes>
+                <Route path="/" element={<Home />} />
+                <Route path="/path" element={<h1>Path</h1>} />
+              </Routes>
+            </MemoryRouter>
+          );
+        });
+
+        function Home() {
+          let navigate = useNavigate();
+          return <button onClick={() => navigate("/path")} />;
+        }
+
+        // @ts-expect-error
+        expect(renderer.toJSON()).toMatchInlineSnapshot(`
+          <button
+            onClick={[Function]}
+          />
+        `);
+
+        // @ts-expect-error
+        let button = renderer.root.findByType("button");
+        TestRenderer.act(() => button.props.onClick());
+
+        // @ts-expect-error
+        expect(renderer.toJSON()).toMatchInlineSnapshot(`
+          <h1>
+            Path
+          </h1>
+        `);
+      });
+
+      it("in a descendant route", () => {
+        let renderer: TestRenderer.ReactTestRenderer;
+        TestRenderer.act(() => {
+          renderer = TestRenderer.create(
+            <MemoryRouter basename="/base" initialEntries={["/base"]}>
+              <Routes>
+                <Route
+                  path="/*"
+                  element={
+                    <Routes>
+                      <Route index element={<Home />} />
+                    </Routes>
+                  }
+                />
+                <Route path="/path" element={<h1>Path</h1>} />
+              </Routes>
+            </MemoryRouter>
+          );
+        });
+
+        function Home() {
+          let navigate = useNavigate();
+          return <button onClick={() => navigate("/path")} />;
+        }
+
+        // @ts-expect-error
+        expect(renderer.toJSON()).toMatchInlineSnapshot(`
+          <button
+            onClick={[Function]}
+          />
+        `);
+
+        // @ts-expect-error
+        let button = renderer.root.findByType("button");
+        TestRenderer.act(() => button.props.onClick());
+
+        // @ts-expect-error
+        expect(renderer.toJSON()).toMatchInlineSnapshot(`
+          <h1>
+            Path
+          </h1>
+        `);
+      });
+    });
+
+    describe("in a RouterProvider", () => {
+      it("in a root route", () => {
+        let router = createMemoryRouter(
+          [
+            {
+              path: "/",
+              Component: Home,
+            },
+            { path: "/path", Component: () => <h1>Path</h1> },
+          ],
+          { basename: "/base", initialEntries: ["/base"] }
+        );
+
+        function Home() {
+          let navigate = useNavigate();
+          return <button onClick={() => navigate("/path")} />;
+        }
+
+        let renderer: TestRenderer.ReactTestRenderer;
+        TestRenderer.act(() => {
+          renderer = TestRenderer.create(<RouterProvider router={router} />);
+        });
+
+        // @ts-expect-error
+        expect(renderer.toJSON()).toMatchInlineSnapshot(`
+          <button
+            onClick={[Function]}
+          />
+        `);
+
+        // @ts-expect-error
+        let button = renderer.root.findByType("button");
+        TestRenderer.act(() => button.props.onClick());
+
+        // @ts-expect-error
+        expect(renderer.toJSON()).toMatchInlineSnapshot(`
+          <h1>
+            Path
+          </h1>
+        `);
+      });
+
+      it("in a descendant route", () => {
+        let router = createMemoryRouter(
+          [
+            {
+              path: "/*",
+              Component() {
+                return (
+                  <Routes>
+                    <Route index element={<Home />} />
+                  </Routes>
+                );
+              },
+            },
+            { path: "/path", Component: () => <h1>Path</h1> },
+          ],
+          { basename: "/base", initialEntries: ["/base"] }
+        );
+
+        function Home() {
+          let navigate = useNavigate();
+          return <button onClick={() => navigate("/path")} />;
+        }
+
+        let renderer: TestRenderer.ReactTestRenderer;
+        TestRenderer.act(() => {
+          renderer = TestRenderer.create(<RouterProvider router={router} />);
+        });
+
+        // @ts-expect-error
+        expect(renderer.toJSON()).toMatchInlineSnapshot(`
+          <button
+            onClick={[Function]}
+          />
+        `);
+
+        // @ts-expect-error
+        let button = renderer.root.findByType("button");
+        TestRenderer.act(() => button.props.onClick());
+
+        // @ts-expect-error
+        expect(renderer.toJSON()).toMatchInlineSnapshot(`
+          <h1>
+            Path
+          </h1>
+        `);
+      });
+    });
+  });
 });
 
 function UseNavigateButton({
diff --git a/packages/react-router/lib/hooks.tsx b/packages/react-router/lib/hooks.tsx
index 4c702f33dd..25891563a3 100644
--- a/packages/react-router/lib/hooks.tsx
+++ b/packages/react-router/lib/hooks.tsx
@@ -188,6 +188,7 @@ function useNavigateUnstable(): NavigateFunction {
     `useNavigate() may be used only in the context of a <Router> component.`
   );
 
+  let dataRouterContext = React.useContext(DataRouterContext);
   let { basename, navigator } = React.useContext(NavigationContext);
   let { matches } = React.useContext(RouteContext);
   let { pathname: locationPathname } = useLocation();
@@ -222,10 +223,12 @@ function useNavigateUnstable(): NavigateFunction {
       );
 
       // If we're operating within a basename, prepend it to the pathname prior
-      // to handing off to history.  If this is a root navigation, then we
-      // navigate to the raw basename which allows the basename to have full
-      // control over the presence of a trailing slash on root links
-      if (basename !== "/") {
+      // to handing off to history (but only if we're not in a data router,
+      // otherwise it'll prepend the basename inside of the router).
+      // If this is a root navigation, then we navigate to the raw basename
+      // which allows the basename to have full control over the presence of a
+      // trailing slash on root links
+      if (dataRouterContext == null && basename !== "/") {
         path.pathname =
           path.pathname === "/"
             ? basename
@@ -238,7 +241,13 @@ function useNavigateUnstable(): NavigateFunction {
         options
       );
     },
-    [basename, navigator, routePathnamesJson, locationPathname]
+    [
+      basename,
+      navigator,
+      routePathnamesJson,
+      locationPathname,
+      dataRouterContext,
+    ]
   );
 
   return navigate;