diff --git a/.changeset/hip-bags-argue.md b/.changeset/hip-bags-argue.md
new file mode 100644
index 00000000..989dd9c0
--- /dev/null
+++ b/.changeset/hip-bags-argue.md
@@ -0,0 +1,5 @@
+---
+"@opennextjs/cloudflare": patch
+---
+
+fix: Ensure the protocol is correct for redirects in server actions during preview mode
diff --git a/packages/cloudflare/src/cli/templates/init.ts b/packages/cloudflare/src/cli/templates/init.ts
index 4ffe33d5..defec664 100644
--- a/packages/cloudflare/src/cli/templates/init.ts
+++ b/packages/cloudflare/src/cli/templates/init.ts
@@ -132,6 +132,12 @@ function populateProcessEnv(url: URL, env: CloudflareEnv) {
       port: url.port,
     },
   });
+
+  /* We need to set this environment variable to make redirects work properly in preview mode.
+   * Next sets this in standalone mode during `startServer`. Without this the protocol would always be `https` here:
+   * https://github.com/vercel/next.js/blob/6b1e48080e896e0d44a05fe009cb79d2d3f91774/packages/next/src/server/app-render/action-handler.ts#L307-L316
+   */
+  process.env.__NEXT_PRIVATE_ORIGIN = url.origin;
 }
 
 /* eslint-disable no-var */