diff --git a/.changeset/smooth-deers-melt.md b/.changeset/smooth-deers-melt.md
new file mode 100644
index 0000000000..9757de5181
--- /dev/null
+++ b/.changeset/smooth-deers-melt.md
@@ -0,0 +1,5 @@
+---
+'@backstage/config-loader': patch
+---
+
+Include `devDependencies` and `optionalDependencies` in the detection of Backstage packages when collecting configuration schema.
diff --git a/packages/config-loader/src/lib/schema/collect.test.ts b/packages/config-loader/src/lib/schema/collect.test.ts
index 479e63c94c..ef9d38faa9 100644
--- a/packages/config-loader/src/lib/schema/collect.test.ts
+++ b/packages/config-loader/src/lib/schema/collect.test.ts
@@ -87,6 +87,8 @@ describe('collectConfigSchemas', () => {
             dependencies: {
               c1: '0.0.0',
               c2: '0.0.0',
+            },
+            devDependencies: {
               '@backstage/mock': '0.0.0',
             },
             configSchema: { ...mockSchema, title: 'b' },
diff --git a/packages/config-loader/src/lib/schema/collect.ts b/packages/config-loader/src/lib/schema/collect.ts
index b53389d499..b363e8e5f3 100644
--- a/packages/config-loader/src/lib/schema/collect.ts
+++ b/packages/config-loader/src/lib/schema/collect.ts
@@ -74,6 +74,8 @@ export async function collectConfigSchemas(
     const pkg = await fs.readJson(pkgPath);
     const depNames = [
       ...Object.keys(pkg.dependencies ?? {}),
+      ...Object.keys(pkg.devDependencies ?? {}),
+      ...Object.keys(pkg.optionalDependencies ?? {}),
       ...Object.keys(pkg.peerDependencies ?? {}),
     ];