diff --git a/.changeset/mighty-lamps-cross.md b/.changeset/mighty-lamps-cross.md
new file mode 100644
index 0000000000..af09263f2e
--- /dev/null
+++ b/.changeset/mighty-lamps-cross.md
@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Fixed backend start command on Windows by removing the use of platform dependent path joins.
diff --git a/packages/cli/src/lib/bundler/config.ts b/packages/cli/src/lib/bundler/config.ts
index 01f323a082..6fc7482dce 100644
--- a/packages/cli/src/lib/bundler/config.ts
+++ b/packages/cli/src/lib/bundler/config.ts
@@ -15,7 +15,7 @@
  */
 
 import fs from 'fs-extra';
-import { resolve as resolvePath, join as joinPath } from 'path';
+import { resolve as resolvePath, posix as posixPath } from 'path';
 import ForkTsCheckerWebpackPlugin from 'fork-ts-checker-webpack-plugin';
 import HtmlWebpackPlugin from 'html-webpack-plugin';
 import ModuleScopePlugin from 'react-dev-utils/ModuleScopePlugin';
@@ -236,7 +236,7 @@ export async function createBackendConfig(
   const { packages } = await getPackages(cliPaths.targetDir);
   const localPackageEntryPoints = packages.flatMap(p => {
     const entryPoints = readEntryPoints((p as ExtendedPackage).packageJson);
-    return entryPoints.map(e => joinPath(p.packageJson.name, e.mount));
+    return entryPoints.map(e => posixPath.join(p.packageJson.name, e.mount));
   });
   const moduleDirs = packages.map(p => resolvePath(p.dir, 'node_modules'));
   // See frontend config