diff --git a/packages/app/src/cli/models/project/project-integration.test.ts b/packages/app/src/cli/models/project/project-integration.test.ts
index d9eca152934..a72994a26da 100644
--- a/packages/app/src/cli/models/project/project-integration.test.ts
+++ b/packages/app/src/cli/models/project/project-integration.test.ts
@@ -79,6 +79,8 @@ dev = "npm run dev"
 
   // package.json (needed by the loader)
   await writeFile(joinPath(dir, 'package.json'), JSON.stringify({name: 'test-app', dependencies: {}}))
+  // Pin npm: getPackageManager walks up to ancestors if no lockfile is found
+  await writeFile(joinPath(dir, 'package-lock.json'), '')
 }
 
 // Load specifications once — this is expensive (loads all extension specs from disk)
diff --git a/packages/app/src/cli/services/app/config/use.test.ts b/packages/app/src/cli/services/app/config/use.test.ts
index 21f6f46ec55..428e0c0a41b 100644
--- a/packages/app/src/cli/services/app/config/use.test.ts
+++ b/packages/app/src/cli/services/app/config/use.test.ts
@@ -45,6 +45,7 @@ describe('use', () => {
       }
       writeFileSync(joinPath(tmp, 'package.json'), '{}')
       writeFileSync(joinPath(tmp, 'shopify.app.toml'), '')
+      writeFileSync(joinPath(tmp, 'package-lock.json'), '')
 
       // When
       await use(options)
diff --git a/packages/cli-kit/src/public/node/node-package-manager.test.ts b/packages/cli-kit/src/public/node/node-package-manager.test.ts
index 5c22f54ecde..8516249743f 100644
--- a/packages/cli-kit/src/public/node/node-package-manager.test.ts
+++ b/packages/cli-kit/src/public/node/node-package-manager.test.ts
@@ -20,6 +20,7 @@ import {
   checkForCachedNewVersion,
   inferPackageManager,
   PackageManager,
+  npmLockfile,
 } from './node-package-manager.js'
 import {captureOutput, exec} from './system.js'
 import {inTemporaryDirectory, mkdir, touchFile, writeFile} from './fs.js'
@@ -845,8 +846,9 @@ describe('writePackageJSON', () => {
 describe('getPackageManager', () => {
   test('finds if npm is being used', async () => {
     await inTemporaryDirectory(async (tmpDir) => {
-      // Given
+      // Given — pin NPM in the temp project
       await writePackageJSON(tmpDir, {name: 'mock name'})
+      await writeFile(joinPath(tmpDir, npmLockfile), '')
 
       // Then
       const packageManager = await getPackageManager(tmpDir)
@@ -878,6 +880,19 @@ describe('getPackageManager', () => {
     })
   })
 
+  test('finds pnpm from a nested workspace package when the lockfile is only at the repo root', async () => {
+    await inTemporaryDirectory(async (tmpDir) => {
+      await writePackageJSON(tmpDir, {name: 'root'})
+      await writeFile(joinPath(tmpDir, 'pnpm-lock.yaml'), '')
+      const nested = joinPath(tmpDir, 'extensions', 'cart-transformer')
+      await mkdir(nested)
+      await writePackageJSON(nested, {name: 'cart-transformer'})
+
+      const packageManager = await getPackageManager(nested)
+      expect(packageManager).toEqual('pnpm')
+    })
+  })
+
   test('falls back to packageManagerFromUserAgent when no package.json is found', async () => {
     await inTemporaryDirectory(async (tmpDir) => {
       // Given — no package.json in tmpDir, stub user agent to yarn
diff --git a/packages/cli-kit/src/public/node/node-package-manager.ts b/packages/cli-kit/src/public/node/node-package-manager.ts
index bdbce5aff7e..b35afb8b6d5 100644
--- a/packages/cli-kit/src/public/node/node-package-manager.ts
+++ b/packages/cli-kit/src/public/node/node-package-manager.ts
@@ -1,7 +1,7 @@
 import {AbortError, BugError} from './error.js'
 import {AbortController, AbortSignal} from './abort.js'
 import {exec} from './system.js'
-import {fileExists, readFile, writeFile, findPathUp, glob} from './fs.js'
+import {fileExists, readFile, writeFile, findPathUp, glob, fileExistsSync} from './fs.js'
 import {dirname, joinPath} from './path.js'
 import {runWithTimer} from './metadata.js'
 import {inferPackageManagerForGlobalCLI} from './is-global.js'
@@ -111,21 +111,29 @@ export function packageManagerFromUserAgent(env = process.env): PackageManager {
 
 /**
  * Returns the dependency manager used in a directory.
+ * Walks upward from `fromDirectory` so workspace packages (e.g. `extensions/my-fn/package.json`)
+ * still resolve to the repo root lockfile (`pnpm-lock.yaml`).
+ * If no lockfile is found, it falls back to the package manager from the user agent.
+ * If the package manager from the user agent is unknown, it returns 'npm'.
  * @param fromDirectory - The starting directory
  * @returns The dependency manager
  */
 export async function getPackageManager(fromDirectory: string): Promise<PackageManager> {
-  const packageJsonPath = await findPathUp('package.json', {cwd: fromDirectory, type: 'file'})
-  if (!packageJsonPath) {
-    return packageManagerFromUserAgent()
+  let current = fromDirectory
+  outputDebug(outputContent`Looking for a lockfile in ${outputToken.path(current)}...`)
+  while (true) {
+    if (fileExistsSync(joinPath(current, yarnLockfile))) return 'yarn'
+    if (fileExistsSync(joinPath(current, pnpmLockfile))) return 'pnpm'
+    if (fileExistsSync(joinPath(current, bunLockfile))) return 'bun'
+    if (fileExistsSync(joinPath(current, npmLockfile))) return 'npm'
+    const parent = dirname(current)
+    if (parent === current) break
+    current = parent
   }
 
-  const directory = dirname(packageJsonPath)
-  outputDebug(outputContent`Obtaining the dependency manager in directory ${outputToken.path(directory)}...`)
+  const pm: PackageManager = packageManagerFromUserAgent()
+  if (pm !== 'unknown') return pm
 
-  if (await fileExists(joinPath(directory, yarnLockfile))) return 'yarn'
-  if (await fileExists(joinPath(directory, pnpmLockfile))) return 'pnpm'
-  if (await fileExists(joinPath(directory, bunLockfile))) return 'bun'
   return 'npm'
 }