diff --git a/.changeset/eighty-fans-rescue.md b/.changeset/eighty-fans-rescue.md
new file mode 100644
index 000000000000..d35560f3a175
--- /dev/null
+++ b/.changeset/eighty-fans-rescue.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare-workers': patch
+---
+
+fix: mark `cloudflare:` packages as external
diff --git a/.changeset/friendly-dragons-hide.md b/.changeset/friendly-dragons-hide.md
new file mode 100644
index 000000000000..ab63b6fc9c0c
--- /dev/null
+++ b/.changeset/friendly-dragons-hide.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare': patch
+---
+
+fix: mark `cloudflare:` packages as external
diff --git a/packages/adapter-cloudflare-workers/index.js b/packages/adapter-cloudflare-workers/index.js
index e21c1b9bdd38..6ab595989024 100644
--- a/packages/adapter-cloudflare-workers/index.js
+++ b/packages/adapter-cloudflare-workers/index.js
@@ -62,7 +62,7 @@ export default function ({ config = 'wrangler.toml' } = {}) {
 				entryPoints: [`${tmp}/entry.js`],
 				outfile: main,
 				bundle: true,
-				external: ['__STATIC_CONTENT_MANIFEST'],
+				external: ['__STATIC_CONTENT_MANIFEST', 'cloudflare:*'],
 				format: 'esm',
 				loader: {
 					'.wasm': 'copy'
diff --git a/packages/adapter-cloudflare/index.js b/packages/adapter-cloudflare/index.js
index ccf6887beca8..46e1c2c3800b 100644
--- a/packages/adapter-cloudflare/index.js
+++ b/packages/adapter-cloudflare/index.js
@@ -57,7 +57,8 @@ export default function (options = {}) {
 				bundle: true,
 				loader: {
 					'.wasm': 'copy'
-				}
+				},
+				external: ['cloudflare:*']
 			});
 		}
 	};