diff --git a/.changeset/fix-astro-cf-pages-env-fallback.md b/.changeset/fix-astro-cf-pages-env-fallback.md
new file mode 100644
index 00000000000..fd452c228c0
--- /dev/null
+++ b/.changeset/fix-astro-cf-pages-env-fallback.md
@@ -0,0 +1,5 @@
+---
+"@clerk/astro": patch
+---
+
+Fix Cloudflare Pages compatibility by falling through to `locals.runtime.env` when `cloudflare:workers` env is missing the requested key
diff --git a/packages/astro/src/server/__tests__/get-safe-env.test.ts b/packages/astro/src/server/__tests__/get-safe-env.test.ts
index 823370af2cc..0a57f8ab8fe 100644
--- a/packages/astro/src/server/__tests__/get-safe-env.test.ts
+++ b/packages/astro/src/server/__tests__/get-safe-env.test.ts
@@ -136,6 +136,21 @@ describe('get-safe-env', () => {
       const env = getSafeEnv({ locals } as any);
       expect(env.sk).toBe('sk_from_cf_workers');
     });
+
+    it('falls back to locals.runtime.env when cloudflareEnv is missing the key (CF Pages)', async () => {
+      // On CF Pages, cloudflare:workers env may have bindings (D1, R2) but
+      // not dashboard secrets like CLERK_SECRET_KEY.
+      vi.doMock('cloudflare:workers', () => ({
+        env: { SOME_OTHER_BINDING: 'value' },
+      }));
+
+      const { initCloudflareEnv, getSafeEnv } = await import('../get-safe-env');
+      await initCloudflareEnv();
+
+      const locals = { runtime: { env: { CLERK_SECRET_KEY: 'sk_from_runtime' } } };
+      const env = getSafeEnv({ locals } as any);
+      expect(env.sk).toBe('sk_from_runtime');
+    });
   });
 });
 
diff --git a/packages/astro/src/server/get-safe-env.ts b/packages/astro/src/server/get-safe-env.ts
index f876aea479b..1d918853592 100644
--- a/packages/astro/src/server/get-safe-env.ts
+++ b/packages/astro/src/server/get-safe-env.ts
@@ -41,8 +41,13 @@ function getContextEnvVar(envVarName: keyof InternalEnv, contextOrLocals: Contex
   // Astro v6+ Cloudflare adapter: env from cloudflare:workers
   // Checked first to avoid the expensive try/catch on locals.runtime.env,
   // which throws on every call in Astro v6 Cloudflare environments.
+  // Falls through when the key is missing — on CF Pages (Astro v5),
+  // cloudflare:workers env may not include dashboard secrets.
   if (cloudflareEnv) {
-    return cloudflareEnv[envVarName];
+    const value = cloudflareEnv[envVarName];
+    if (value !== undefined) {
+      return value;
+    }
   }
 
   // Astro v4/v5 Cloudflare adapter: env is on locals.runtime.env