diff --git a/.changeset/brisk-otters-glow.md b/.changeset/brisk-otters-glow.md
new file mode 100644
index 000000000000..798b6f925f28
--- /dev/null
+++ b/.changeset/brisk-otters-glow.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-auto': patch
+---
+
+fix: convert resolved adapter path to a file URL before importing, so builds work on Windows
diff --git a/.changeset/tall-frogs-argue.md b/.changeset/tall-frogs-argue.md
new file mode 100644
index 000000000000..54c3f7723264
--- /dev/null
+++ b/.changeset/tall-frogs-argue.md
@@ -0,0 +1,6 @@
+---
+'@sveltejs/kit': patch
+'@sveltejs/package': patch
+---
+
+fix: import resolved peer dependencies as file URLs so project-relative resolution works on Windows
diff --git a/packages/adapter-auto/index.js b/packages/adapter-auto/index.js
index 5bb56c3be9a1..f2e5edf07c80 100644
--- a/packages/adapter-auto/index.js
+++ b/packages/adapter-auto/index.js
@@ -1,4 +1,5 @@
 import { execSync } from 'node:child_process';
+import { pathToFileURL } from 'node:url';
 import { adapters } from './adapters.js';
 import path from 'node:path';
 import fs from 'node:fs';
@@ -122,7 +123,7 @@ async function get_adapter() {
 	}
 
 	/** @type {{ default: () => Adapter }} */
-	const module = await import(resolved);
+	const module = await import(pathToFileURL(resolved).href);
 
 	const adapter = module.default();
 
diff --git a/packages/kit/src/utils/import.js b/packages/kit/src/utils/import.js
index 44b26a276254..19b93b119db8 100644
--- a/packages/kit/src/utils/import.js
+++ b/packages/kit/src/utils/import.js
@@ -1,5 +1,6 @@
 import fs from 'node:fs';
 import path from 'node:path';
+import { pathToFileURL } from 'node:url';
 
 /**
  * Resolves a peer dependency relative to the current working directory.
@@ -51,7 +52,7 @@ function resolve_peer(dependency, root) {
  */
 export async function import_peer(dependency, root) {
 	try {
-		return await import(/* @vite-ignore */ resolve_peer(dependency, root));
+		return await import(/* @vite-ignore */ pathToFileURL(resolve_peer(dependency, root)).href);
 	} catch {
 		return await import(/* @vite-ignore */ dependency);
 	}
diff --git a/packages/package/src/config.js b/packages/package/src/config.js
index e78727c6999b..94544be7d471 100644
--- a/packages/package/src/config.js
+++ b/packages/package/src/config.js
@@ -1,6 +1,7 @@
 import path from 'node:path';
 import process from 'node:process';
 import fs from 'node:fs';
+import { pathToFileURL } from 'node:url';
 
 /**
  * Loads and validates the SvelteKit config
@@ -39,7 +40,7 @@ export function load_pkg_json(cwd = process.cwd()) {
  */
 async function import_peer(dependency, root) {
 	try {
-		return await import(/* @vite-ignore */ resolve_peer(dependency, root));
+		return await import(/* @vite-ignore */ pathToFileURL(resolve_peer(dependency, root)).href);
 	} catch {
 		return await import(/* @vite-ignore */ dependency);
 	}