diff --git a/.changeset/warm-tigers-knock.md b/.changeset/warm-tigers-knock.md
new file mode 100644
index 000000000000..051d268a7755
--- /dev/null
+++ b/.changeset/warm-tigers-knock.md
@@ -0,0 +1,5 @@
+---
+'@astrojs/vercel': patch
+---
+
+Fixes edge middleware `next()` dropping the HTTP method and body when forwarding requests to the serverless function, which caused non-GET API routes (POST, PUT, PATCH, DELETE) to return 404
diff --git a/packages/integrations/vercel/src/serverless/middleware.ts b/packages/integrations/vercel/src/serverless/middleware.ts
index 0f215ee84aa4..058d78296ba3 100644
--- a/packages/integrations/vercel/src/serverless/middleware.ts
+++ b/packages/integrations/vercel/src/serverless/middleware.ts
@@ -127,12 +127,14 @@ export default async function middleware(request, context) {
 	const next = async () => {
 		const { vercel, ...locals } = ctx.locals;
 		const response = await fetch(new URL('/${NODE_PATH}', request.url), {
+			method: request.method,
 			headers: {
 				...Object.fromEntries(request.headers.entries()),
 				'${ASTRO_MIDDLEWARE_SECRET_HEADER}': '${middlewareSecret}',
 				'${ASTRO_PATH_HEADER}': request.url.replace(origin, ''),
 				'${ASTRO_LOCALS_HEADER}': trySerializeLocals(locals)
-			}
+			},
+			...(request.body ? { body: request.body, duplex: 'half' } : {}),
 		});
 		return new Response(response.body, {
 			status: response.status,
diff --git a/packages/integrations/vercel/test/edge-middleware.test.js b/packages/integrations/vercel/test/edge-middleware.test.js
index d6313d483ab6..89c2a3c3f472 100644
--- a/packages/integrations/vercel/test/edge-middleware.test.js
+++ b/packages/integrations/vercel/test/edge-middleware.test.js
@@ -42,6 +42,33 @@ describe('Vercel edge middleware', () => {
 		assert.ok((await response.text()).length, 'Body is included');
 	});
 
+	it('edge middleware forwards HTTP method and body', async () => {
+		const entry = new URL(
+			'../.vercel/output/functions/_middleware.func/middleware.mjs',
+			build.config.outDir,
+		);
+		const module = await import(entry);
+
+		const originalFetch = globalThis.fetch;
+		let captured;
+		globalThis.fetch = async (_url, opts) => {
+			captured = opts;
+			return new Response('ok', { status: 200 });
+		};
+		try {
+			const request = new Request('http://example.com/api/test', {
+				method: 'POST',
+				body: '{"data":"test"}',
+				headers: { 'Content-Type': 'application/json' },
+			});
+			await module.default(request, {});
+			assert.equal(captured.method, 'POST', 'forwards the HTTP method');
+			assert.ok(captured.body, 'forwards the request body');
+		} finally {
+			globalThis.fetch = originalFetch;
+		}
+	});
+
 	// TODO: The path here seems to be inconsistent?
 	it.skip('with edge handle file, should successfully build the middleware', async () => {
 		const fixture = await loadFixture({