diff --git a/.changeset/fix-spa-vite-preview.md b/.changeset/fix-spa-vite-preview.md
new file mode 100644
index 0000000000..23c077eec1
--- /dev/null
+++ b/.changeset/fix-spa-vite-preview.md
@@ -0,0 +1,5 @@
+---
+"@react-router/dev": patch
+---
+
+fix(vite): Skip SSR middleware in preview server for SPA mode
diff --git a/contributors.yml b/contributors.yml
index ff24ac4b77..e8a8cd30dd 100644
--- a/contributors.yml
+++ b/contributors.yml
@@ -29,6 +29,7 @@
 - amsal
 - Andarist
 - andreasottosson-polestar
+- andreiborza
 - andreiduca
 - antonmontrezor
 - appden
diff --git a/integration/vite-preview-test.ts b/integration/vite-preview-test.ts
index 65eb1611fe..bdf23eecf8 100644
--- a/integration/vite-preview-test.ts
+++ b/integration/vite-preview-test.ts
@@ -314,4 +314,74 @@ test.describe("Vite preview", () => {
       "Product 123",
     );
   });
+
+  test("serves SPA mode app with vite preview", async ({
+    vitePreview,
+    page,
+  }) => {
+    const files: Files = async ({ port }) => ({
+      "react-router.config.ts": reactRouterConfig({
+        ssr: false,
+        v8_viteEnvironmentApi: true,
+      }),
+      "vite.config.ts": await viteConfig.basic({
+        port,
+        templateName: "vite-6-template",
+      }),
+      "app/root.tsx": tsx`
+        import { Links, Meta, Outlet, Scripts } from "react-router";
+
+        export default function Root() {
+          return (
+            <html lang="en">
+              <head>
+                <Meta />
+                <Links />
+              </head>
+              <body>
+                <div id="content">
+                  <h1>SPA Mode</h1>
+                  <Outlet />
+                </div>
+                <Scripts />
+              </body>
+            </html>
+          );
+        }
+      `,
+      "app/routes/_index.tsx": tsx`
+        export default function IndexRoute() {
+          return (
+            <div id="index">
+              <h2 data-title>Index</h2>
+              <p data-spa-mode>SPA Mode Enabled</p>
+            </div>
+          );
+        }
+      `,
+      "app/routes/about.tsx": tsx`
+        export default function AboutRoute() {
+          return (
+            <div id="about">
+              <h2 data-title>About</h2>
+              <p>About page in SPA mode</p>
+            </div>
+          );
+        }
+      `,
+    });
+
+    const { port } = await vitePreview(files, "vite-6-template");
+    await page.goto(`http://localhost:${port}/`, {
+      waitUntil: "networkidle",
+    });
+
+    // Ensure no errors on page load (this would fail without the fix)
+    expect(page.errors).toEqual([]);
+
+    await expect(page.locator("#index [data-title]")).toHaveText("Index");
+    await expect(page.locator("#index [data-spa-mode]")).toHaveText(
+      "SPA Mode Enabled",
+    );
+  });
 });
diff --git a/packages/react-router-dev/vite/plugin.ts b/packages/react-router-dev/vite/plugin.ts
index 4d11d253af..7fc5480541 100644
--- a/packages/react-router-dev/vite/plugin.ts
+++ b/packages/react-router-dev/vite/plugin.ts
@@ -1688,6 +1688,11 @@ export const reactRouterVitePlugin: ReactRouterVitePlugin = () => {
       },
       configurePreviewServer(previewServer) {
         return () => {
+          // Skip SSR handling in SPA mode
+          if (!ctx.reactRouterConfig.ssr) {
+            return;
+          }
+
           // Handle SSR requests in preview mode using the built server bundle
           previewServer.middlewares.use(async (req, res, next) => {
             try {
