diff --git a/.changeset/precompress-markdown-adapter-node.md b/.changeset/precompress-markdown-adapter-node.md
new file mode 100644
index 000000000000..4f8d4469f111
--- /dev/null
+++ b/.changeset/precompress-markdown-adapter-node.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-node': minor
+---
+
+feat: precompress prerendered `.md` and `.mdx` files
diff --git a/.changeset/precompress-markdown-adapter-static.md b/.changeset/precompress-markdown-adapter-static.md
new file mode 100644
index 000000000000..268dff1df6b4
--- /dev/null
+++ b/.changeset/precompress-markdown-adapter-static.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-static': minor
+---
+
+feat: precompress prerendered `.md` and `.mdx` files
diff --git a/.changeset/precompress-markdown-files.md b/.changeset/precompress-markdown-files.md
new file mode 100644
index 000000000000..efc5df85a6fb
--- /dev/null
+++ b/.changeset/precompress-markdown-files.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': minor
+---
+
+feat: precompress `.md` and `.mdx` files when adapters call `builder.compress()`
diff --git a/packages/kit/src/core/adapt/builder.js b/packages/kit/src/core/adapt/builder.js
index 42ff2145db31..67c50d34b1d6 100644
--- a/packages/kit/src/core/adapt/builder.js
+++ b/packages/kit/src/core/adapt/builder.js
@@ -19,7 +19,19 @@ import { find_server_assets } from '../generate_manifest/find_server_assets.js';
 import { reserved } from '../env.js';
 
 const pipe = promisify(pipeline);
-const extensions = ['.html', '.js', '.mjs', '.json', '.css', '.svg', '.xml', '.wasm', '.txt'];
+const extensions = [
+	'.html',
+	'.js',
+	'.mjs',
+	'.json',
+	'.css',
+	'.svg',
+	'.xml',
+	'.wasm',
+	'.txt',
+	'.md',
+	'.mdx'
+];
 
 /**
  * Creates the Builder which is passed to adapters for building the application.
diff --git a/packages/kit/src/core/adapt/builder.spec.js b/packages/kit/src/core/adapt/builder.spec.js
index b69c7b8296bb..1761dc179baa 100644
--- a/packages/kit/src/core/adapt/builder.spec.js
+++ b/packages/kit/src/core/adapt/builder.spec.js
@@ -65,12 +65,20 @@ test('compress files', async () => {
 		route_data: []
 	});
 
-	const target = fileURLToPath(new URL('./fixtures/compress/foo.css', import.meta.url));
-	rmSync(target + '.br', { force: true });
-	rmSync(target + '.gz', { force: true });
-	await builder.compress(dirname(target));
-	assert.ok(existsSync(target + '.br'));
-	assert.ok(existsSync(target + '.gz'));
+	const targets = [
+		fileURLToPath(new URL('./fixtures/compress/foo.css', import.meta.url)),
+		fileURLToPath(new URL('./fixtures/compress/foo.md', import.meta.url)),
+		fileURLToPath(new URL('./fixtures/compress/foo.mdx', import.meta.url))
+	];
+	for (const target of targets) {
+		rmSync(target + '.br', { force: true });
+		rmSync(target + '.gz', { force: true });
+	}
+	await builder.compress(dirname(targets[0]));
+	for (const target of targets) {
+		assert.ok(existsSync(target + '.br'));
+		assert.ok(existsSync(target + '.gz'));
+	}
 });
 
 test('instrument generates facade with posix paths', () => {
diff --git a/packages/kit/src/core/adapt/fixtures/compress/foo.md b/packages/kit/src/core/adapt/fixtures/compress/foo.md
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/kit/src/core/adapt/fixtures/compress/foo.mdx b/packages/kit/src/core/adapt/fixtures/compress/foo.mdx
new file mode 100644
index 000000000000..e69de29bb2d1