diff --git a/app/services/ci/runners/unassign_runner_service.rb b/app/services/ci/runners/unassign_runner_service.rb
index a38a41960213f7aedd5c25d2cfef9b25da389a14..1e46cf6add85e752d647933046eb83e664044833 100644
--- a/app/services/ci/runners/unassign_runner_service.rb
+++ b/app/services/ci/runners/unassign_runner_service.rb
@@ -6,8 +6,9 @@ class UnassignRunnerService
       # @param [Ci::RunnerProject] runner_project the runner/project association to destroy
       # @param [User] user the user performing the operation
       def initialize(runner_project, user)
-        @runner = runner_project.runner
         @runner_project = runner_project
+        @runner = runner_project.runner
+        @project = runner_project.project
         @user = user
       end
 
@@ -16,6 +17,12 @@ def execute
 
         @runner_project.destroy
       end
+
+      private
+
+      attr_reader :runner, :project, :user
     end
   end
 end
+
+Ci::Runners::UnassignRunnerService.prepend_mod
diff --git a/ee/app/services/ee/ci/runners/unassign_runner_service.rb b/ee/app/services/ee/ci/runners/unassign_runner_service.rb
new file mode 100644
index 0000000000000000000000000000000000000000..e7a0440bea6a75254f2c67461279d8a5b4254cb8
--- /dev/null
+++ b/ee/app/services/ee/ci/runners/unassign_runner_service.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module EE
+  module Ci
+    module Runners
+      module UnassignRunnerService
+        extend ::Gitlab::Utils::Override
+        include ::Audit::Changes
+
+        override :execute
+        def execute
+          result = super
+
+          audit_log_event if result
+
+          result
+        end
+
+        private
+
+        AUDIT_MESSAGE = 'Unassigned CI runner from project'
+
+        def audit_log_event
+          ::AuditEvents::RunnerCustomAuditEventService.new(runner, user, project, AUDIT_MESSAGE).track_event
+        end
+      end
+    end
+  end
+end
diff --git a/ee/spec/services/ci/runners/unassign_runner_service_spec.rb b/ee/spec/services/ci/runners/unassign_runner_service_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..920a1ecf8995bd89805e7c4488db6ba8b1a78f36
--- /dev/null
+++ b/ee/spec/services/ci/runners/unassign_runner_service_spec.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe ::Ci::Runners::UnassignRunnerService, '#execute' do
+  let_it_be(:owner_project) { create(:project) }
+  let_it_be(:other_project) { create(:project) }
+  let_it_be(:project_runner) { create(:ci_runner, :project, projects: [owner_project, other_project]) }
+
+  let(:runner_project) { project_runner.runner_projects.last }
+
+  let(:audit_service) { instance_double(::AuditEvents::RunnerCustomAuditEventService) }
+
+  subject { described_class.new(runner_project, user).execute }
+
+  context 'with unauthorized user' do
+    let(:user) { build(:user) }
+
+    it 'does not call assign_to on runner and returns false', :aggregate_failures do
+      expect(project_runner).not_to receive(:assign_to)
+      expect(::AuditEvents::RunnerCustomAuditEventService).not_to receive(:new)
+
+      is_expected.to be_falsey
+    end
+  end
+
+  context 'with admin user', :enable_admin_mode do
+    let(:user) { create_default(:admin) }
+
+    before do
+      expect(audit_service).to receive(:track_event).once.and_return('track_event_return_value')
+    end
+
+    it 'calls track_event on RunnerCustomAuditEventService and returns the runner_project', :aggregate_failures do
+      expect(runner_project).to receive(:destroy).once.and_call_original
+      expect(::AuditEvents::RunnerCustomAuditEventService).to receive(:new)
+        .with(project_runner, user, other_project, 'Unassigned CI runner from project')
+        .once.and_return(audit_service)
+
+      is_expected.to eq(runner_project)
+    end
+  end
+end