diff --git a/app/services/system_hooks_service.rb b/app/services/system_hooks_service.rb
index 868fa7b3f21..af0ddbe5934 100644
--- a/app/services/system_hooks_service.rb
+++ b/app/services/system_hooks_service.rb
@@ -24,10 +24,9 @@ class SystemHooksService
         key: model.key,
         id: model.id
       )
+ 
       if model.user
-        data.merge!(
-          username: model.user.username
-        )
+        data[:username] = model.user.username
       end
     when Project
       data.merge!(project_data(model))
@@ -35,8 +34,6 @@ class SystemHooksService
       if event == :rename || event == :transfer
         data[:old_path_with_namespace] = model.old_path_with_namespace
       end
-
-      data
     when User
       data.merge!({
         name: model.name,
@@ -59,6 +56,8 @@ class SystemHooksService
     when GroupMember
       data.merge!(group_member_data(model))
     end
+    
+    data
   end
 
   def build_event_name(model, event)
diff --git a/changelogs/unreleased/bugfix-systemhook.yml b/changelogs/unreleased/bugfix-systemhook.yml
new file mode 100644
index 00000000000..4c4d0dcc7a2
--- /dev/null
+++ b/changelogs/unreleased/bugfix-systemhook.yml
@@ -0,0 +1,4 @@
+---
+title: Fix bug when system hook for deploy key
+merge_request: 9796
+author: billy.lb
diff --git a/spec/services/system_hooks_service_spec.rb b/spec/services/system_hooks_service_spec.rb
index db9f1231682..11037a4917b 100644
--- a/spec/services/system_hooks_service_spec.rb
+++ b/spec/services/system_hooks_service_spec.rb
@@ -5,6 +5,7 @@ describe SystemHooksService, services: true do
   let(:project)       { create :project }
   let(:project_member) { create :project_member }
   let(:key)           { create(:key, user: user) }
+  let(:deploy_key)    { create(:key) }
   let(:group)         { create(:group) }
   let(:group_member)  { create(:group_member) }
 
@@ -18,6 +19,8 @@ describe SystemHooksService, services: true do
     it { expect(event_data(project_member, :destroy)).to include(:event_name, :created_at, :updated_at, :project_name, :project_path, :project_path_with_namespace, :project_id, :user_name, :user_username, :user_email, :user_id, :access_level, :project_visibility) }
     it { expect(event_data(key, :create)).to include(:username, :key, :id) }
     it { expect(event_data(key, :destroy)).to include(:username, :key, :id) }
+    it { expect(event_data(deploy_key, :create)).to include(:key, :id) }
+    it { expect(event_data(deploy_key, :destroy)).to include(:key, :id) }
 
     it do
       project.old_path_with_namespace = 'renamed_from_path'