diff --git a/app/serializers/diffs_metadata_entity.rb b/app/serializers/diffs_metadata_entity.rb
index 7b0de3bce4e4a6b9fdaaadbde116a5353e736862..681e629244fac725ec5c18a57da7ac2ef927cae9 100644
--- a/app/serializers/diffs_metadata_entity.rb
+++ b/app/serializers/diffs_metadata_entity.rb
@@ -18,8 +18,30 @@ class DiffsMetadataEntity < DiffsEntity
     options[:merge_request].can_be_merged_by?(request.current_user)
   end
 
+  expose :project_path
+  expose :project_name
+
+  expose :username
+  expose :user_full_name
+
   private
 
+  def project_path
+    request.project&.full_path
+  end
+
+  def project_name
+    request.project&.name
+  end
+
+  def username
+    request.current_user&.username
+  end
+
+  def user_full_name
+    request.current_user&.name
+  end
+
   def presenter(merge_request)
     @presenters ||= {}
     @presenters[merge_request] ||= MergeRequestPresenter.new(merge_request, current_user: request.current_user) # rubocop: disable CodeReuse/Presenter
diff --git a/changelogs/unreleased/291027-extend-diffs_metadata-with-project-and-user-names.yml b/changelogs/unreleased/291027-extend-diffs_metadata-with-project-and-user-names.yml
new file mode 100644
index 0000000000000000000000000000000000000000..8d47ba925931be0134e3f51f14c322c366e85716
--- /dev/null
+++ b/changelogs/unreleased/291027-extend-diffs_metadata-with-project-and-user-names.yml
@@ -0,0 +1,5 @@
+---
+title: Add additional fields to diff_metadata.json endpoint
+merge_request: 50666
+author:
+type: changed
diff --git a/spec/serializers/diffs_metadata_entity_spec.rb b/spec/serializers/diffs_metadata_entity_spec.rb
index e8cbc2076d72c530bc8ec3ccace3f85183788e53..f6993d4652eeb4a0601726c5243f5776427309a9 100644
--- a/spec/serializers/diffs_metadata_entity_spec.rb
+++ b/spec/serializers/diffs_metadata_entity_spec.rb
@@ -31,6 +31,7 @@
         :merge_request_diffs, :context_commits,
         :definition_path_prefix, :source_branch_exists,
         :can_merge, :conflict_resolution_path, :has_conflicts,
+        :project_name, :project_path, :user_full_name, :username,
         # Attributes
         :diff_files
       )