diff --git a/CHANGELOG b/CHANGELOG
index 104f37003c9..ae0322a3ff9 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,7 @@ v 8.12.0 (unreleased)
   - Added 'only_allow_merge_if_build_succeeds' project setting in the API. !5930 (Duck)
   - Reduce number of database queries on builds tab
   - Use the default branch for displaying the project icon instead of master !5792 (Hannes Rosenögger)
+  - Adds response mime type to transaction metric action when it's not HTML
 
 v 8.11.2 (unreleased)
   - Show "Create Merge Request" widget for push events to fork projects on the source project
diff --git a/lib/gitlab/metrics/rack_middleware.rb b/lib/gitlab/metrics/rack_middleware.rb
index b4493bf44d2..01c96a6fe96 100644
--- a/lib/gitlab/metrics/rack_middleware.rb
+++ b/lib/gitlab/metrics/rack_middleware.rb
@@ -4,6 +4,17 @@ module Gitlab
     class RackMiddleware
       CONTROLLER_KEY = 'action_controller.instance'
       ENDPOINT_KEY   = 'api.endpoint'
+      CONTENT_TYPES = {
+        'text/html' => :html,
+        'text/plain' => :txt,
+        'application/json' => :json,
+        'text/js' => :js,
+        'application/atom+xml' => :atom,
+        'image/png' => :png,
+        'image/jpeg' => :jpeg,
+        'image/gif' => :gif,
+        'image/svg+xml' => :svg
+      }
 
       def initialize(app)
         @app = app
@@ -46,8 +57,15 @@ module Gitlab
       end
 
       def tag_controller(trans, env)
-        controller   = env[CONTROLLER_KEY]
-        trans.action = "#{controller.class.name}##{controller.action_name}"
+        controller = env[CONTROLLER_KEY]
+        action = "#{controller.class.name}##{controller.action_name}"
+        suffix = CONTENT_TYPES[controller.content_type]
+
+        if suffix && suffix != :html
+          action += ".#{suffix}"
+        end
+
+        trans.action = action
       end
 
       def tag_endpoint(trans, env)
diff --git a/spec/lib/gitlab/metrics/rack_middleware_spec.rb b/spec/lib/gitlab/metrics/rack_middleware_spec.rb
index a30cb2a5e38..bcaffd27909 100644
--- a/spec/lib/gitlab/metrics/rack_middleware_spec.rb
+++ b/spec/lib/gitlab/metrics/rack_middleware_spec.rb
@@ -19,7 +19,7 @@ describe Gitlab::Metrics::RackMiddleware do
     end
 
     it 'tags a transaction with the name and action of a controller' do
-      klass      = double(:klass, name: 'TestController')
+      klass      = double(:klass, name: 'TestController', content_type: 'text/html')
       controller = double(:controller, class: klass, action_name: 'show')
 
       env['action_controller.instance'] = controller
@@ -32,7 +32,7 @@ describe Gitlab::Metrics::RackMiddleware do
       middleware.call(env)
     end
 
-    it 'tags a transaction with the method andpath of the route in the grape endpoint' do
+    it 'tags a transaction with the method and path of the route in the grape endpoint' do
       route    = double(:route, route_method: "GET", route_path: "/:version/projects/:id/archive(.:format)")
       endpoint = double(:endpoint, route: route)
 
@@ -87,17 +87,30 @@ describe Gitlab::Metrics::RackMiddleware do
 
   describe '#tag_controller' do
     let(:transaction) { middleware.transaction_from_env(env) }
+    let(:content_type) { 'text/html' }
 
-    it 'tags a transaction with the name and action of a controller' do
+    before do
       klass      = double(:klass, name: 'TestController')
-      controller = double(:controller, class: klass, action_name: 'show')
+      controller = double(:controller, class: klass, action_name: 'show', content_type: content_type)
 
       env['action_controller.instance'] = controller
+    end
 
+    it 'tags a transaction with the name and action of a controller' do
       middleware.tag_controller(transaction, env)
 
       expect(transaction.action).to eq('TestController#show')
     end
+
+    context 'when the response content type is not :html' do
+      let(:content_type) { 'application/json' }
+
+      it 'appends the mime type to the transaction action' do
+        middleware.tag_controller(transaction, env)
+
+        expect(transaction.action).to eq('TestController#show.json')
+      end
+    end
   end
 
   describe '#tag_endpoint' do