diff --git a/.changeset/hip-fans-decide.md b/.changeset/hip-fans-decide.md
new file mode 100644
index 0000000000..ecdf6d8a4d
--- /dev/null
+++ b/.changeset/hip-fans-decide.md
@@ -0,0 +1,5 @@
+---
+'@backstage/cli-node': patch
+---
+
+Add definition for the new `backstage.inline` field in `package.json`.
diff --git a/packages/cli-node/api-report.md b/packages/cli-node/api-report.md
index 9f7e525048..f22583dd25 100644
--- a/packages/cli-node/api-report.md
+++ b/packages/cli-node/api-report.md
@@ -18,6 +18,7 @@ export interface BackstagePackageJson {
   backstage?: {
     role?: PackageRole;
     moved?: string;
+    inline?: boolean;
     pluginId?: string | null;
     pluginPackage?: string;
     pluginPackages?: string[];
diff --git a/packages/cli-node/src/monorepo/PackageGraph.ts b/packages/cli-node/src/monorepo/PackageGraph.ts
index c8877803d5..69ec99c2dd 100644
--- a/packages/cli-node/src/monorepo/PackageGraph.ts
+++ b/packages/cli-node/src/monorepo/PackageGraph.ts
@@ -47,6 +47,15 @@ export interface BackstagePackageJson {
     role?: PackageRole;
     moved?: string;
 
+    /**
+     * If set to `true`, the package will be treated as an internal package
+     * where any imports will be inlined into the consuming package.
+     *
+     * When set to `true`, the top-level `private` field must be set to `true`
+     * as well.
+     */
+    inline?: boolean;
+
     /**
      * The ID of the plugin if this is a plugin package. Must always be set for plugin and module packages, and may be set for library packages. A `null` value means that the package is explicitly not a plugin package.
      */