diff --git a/app/presenters/merge_request_presenter.rb b/app/presenters/merge_request_presenter.rb
index c59e73f824c06416d2b12acbcd8667ee2f8a52e3..af164858408c851cf1b8c26c8f5c910d1ee6845e 100644
--- a/app/presenters/merge_request_presenter.rb
+++ b/app/presenters/merge_request_presenter.rb
@@ -98,6 +98,12 @@ def target_branch_commits_path
     end
   end
 
+  def target_branch_path
+    if target_branch_exists?
+      project_branch_path(project, target_branch)
+    end
+  end
+
   def source_branch_path
     if source_branch_exists?
       project_branch_path(source_project, source_branch)
diff --git a/app/serializers/merge_request_for_pipeline_entity.rb b/app/serializers/merge_request_for_pipeline_entity.rb
new file mode 100644
index 0000000000000000000000000000000000000000..7779ddfd65a5c50674a4eb4a58f3bf027333caaf
--- /dev/null
+++ b/app/serializers/merge_request_for_pipeline_entity.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class MergeRequestForPipelineEntity < Grape::Entity
+  include RequestAwareEntity
+
+  expose :iid
+
+  expose :path do |merge_request|
+    project_merge_request_path(merge_request.project, merge_request)
+  end
+
+  expose :title
+  expose :source_branch
+  expose :source_branch_path
+  expose :target_branch
+  expose :target_branch_path
+end
diff --git a/app/serializers/pipeline_entity.rb b/app/serializers/pipeline_entity.rb
index c2990cb5159013aa5baf9644825e27af3e37adb8..5ac1e590d39e7038b38257a557dcf3b86b7ca877 100644
--- a/app/serializers/pipeline_entity.rb
+++ b/app/serializers/pipeline_entity.rb
@@ -28,6 +28,7 @@ class PipelineEntity < Grape::Entity
     expose :can_retry?, as: :retryable
     expose :can_cancel?, as: :cancelable
     expose :failure_reason?, as: :failure_reason
+    expose :detached_merge_request_pipeline?, as: :detached
   end
 
   expose :details do
@@ -36,6 +37,10 @@ class PipelineEntity < Grape::Entity
     expose :finished_at
   end
 
+  expose :merge_request, if: -> (*) { has_presentable_merge_request? }, with: MergeRequestForPipelineEntity do |pipeline|
+    pipeline.merge_request.present(current_user: request.current_user)
+  end
+
   expose :ref do
     expose :name do |pipeline|
       pipeline.ref
@@ -81,6 +86,11 @@ def can_cancel?
       pipeline.cancelable?
   end
 
+  def has_presentable_merge_request?
+    pipeline.triggered_by_merge_request? &&
+      can?(request.current_user, :read_merge_request, pipeline.merge_request)
+  end
+
   def detailed_status
     pipeline.detailed_status(request.current_user)
   end
diff --git a/app/serializers/pipeline_serializer.rb b/app/serializers/pipeline_serializer.rb
index 7451433a8418e366546a9db8d11631970194742c..dbbeca9431d827600bf6d33b4ff657de33032f68 100644
--- a/app/serializers/pipeline_serializer.rb
+++ b/app/serializers/pipeline_serializer.rb
@@ -15,6 +15,7 @@ def represent(resource, opts = {})
         :manual_actions,
         :scheduled_actions,
         :artifacts,
+        :merge_request,
         {
           pending_builds: :project,
           project: [:route, { namespace: :route }],
diff --git a/changelogs/unreleased/expose-merge-request-entity-for-pipelines.yml b/changelogs/unreleased/expose-merge-request-entity-for-pipelines.yml
new file mode 100644
index 0000000000000000000000000000000000000000..e5cbc87ba249f9f5164dbdd9afa1ec217d6121a7
--- /dev/null
+++ b/changelogs/unreleased/expose-merge-request-entity-for-pipelines.yml
@@ -0,0 +1,5 @@
+---
+title: Expose merge request entity for pipelines
+merge_request: 25679
+author:
+type: added
diff --git a/spec/presenters/merge_request_presenter_spec.rb b/spec/presenters/merge_request_presenter_spec.rb
index bafcddebbb7809c9ae9cacff1f6bea13fa6ab24e..02cefcbc916bf09e339eef9130a0ddcba9a1fd46 100644
--- a/spec/presenters/merge_request_presenter_spec.rb
+++ b/spec/presenters/merge_request_presenter_spec.rb
@@ -392,6 +392,29 @@
     end
   end
 
+  describe '#target_branch_path' do
+    subject do
+      described_class.new(resource, current_user: user).target_branch_path
+    end
+
+    context 'when target branch exists' do
+      it 'returns path' do
+        allow(resource).to receive(:target_branch_exists?) { true }
+
+        is_expected
+          .to eq("/#{resource.source_project.full_path}/branches/#{resource.target_branch}")
+      end
+    end
+
+    context 'when target branch does not exist' do
+      it 'returns nil' do
+        allow(resource).to receive(:target_branch_exists?) { false }
+
+        is_expected.to be_nil
+      end
+    end
+  end
+
   describe '#source_branch_with_namespace_link' do
     subject do
       described_class.new(resource, current_user: user).source_branch_with_namespace_link
diff --git a/spec/serializers/merge_request_for_pipeline_entity_spec.rb b/spec/serializers/merge_request_for_pipeline_entity_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..e49b45bc7d78a447ee03db1b3cd93d916792636e
--- /dev/null
+++ b/spec/serializers/merge_request_for_pipeline_entity_spec.rb
@@ -0,0 +1,29 @@
+require 'spec_helper'
+
+describe MergeRequestForPipelineEntity do
+  let(:project) { create(:project, :repository) }
+  let(:user) { create(:user) }
+  let(:request) { EntityRequest.new(project: project) }
+  let(:merge_request) { create(:merge_request, target_project: project, source_project: project) }
+  let(:presenter) { MergeRequestPresenter.new(merge_request, current_user: user) }
+
+  let(:entity) do
+    described_class.new(presenter, request: request)
+  end
+
+  before do
+    project.add_developer(user)
+  end
+
+  context 'as json' do
+    subject { entity.as_json }
+
+    it 'exposes needed attributes' do
+      expect(subject).to include(
+        :iid, :path, :title,
+        :source_branch, :source_branch_path,
+        :target_branch, :target_branch_path
+      )
+    end
+  end
+end
diff --git a/spec/serializers/pipeline_entity_spec.rb b/spec/serializers/pipeline_entity_spec.rb
index 774486dcb6d710a0b8857af54aac44907042b548..110408621298817bc77df575c7a9f36150cd7289 100644
--- a/spec/serializers/pipeline_entity_spec.rb
+++ b/spec/serializers/pipeline_entity_spec.rb
@@ -1,6 +1,8 @@
 require 'spec_helper'
 
 describe PipelineEntity do
+  include Gitlab::Routing
+
   set(:user) { create(:user) }
   let(:request) { double('request') }
 
@@ -128,5 +130,48 @@
           .to eq 'CI/CD YAML configuration error!'
       end
     end
+
+    context 'when pipeline is detached merge request pipeline' do
+      let(:merge_request) { create(:merge_request, :with_merge_request_pipeline) }
+      let(:project) { merge_request.target_project }
+      let(:pipeline) { merge_request.merge_request_pipelines.first }
+
+      it 'makes detached flag true' do
+        expect(subject[:flags][:detached]).to be_truthy
+      end
+
+      context 'when user is a developer' do
+        before do
+          project.add_developer(user)
+        end
+
+        it 'has merge request information' do
+          expect(subject[:merge_request][:iid]).to eq(merge_request.iid)
+
+          expect(project_merge_request_path(project, merge_request))
+            .to include(subject[:merge_request][:path])
+
+          expect(subject[:merge_request][:title]).to eq(merge_request.title)
+
+          expect(subject[:merge_request][:source_branch])
+            .to eq(merge_request.source_branch)
+
+          expect(project_branch_path(project, merge_request.source_branch))
+            .to include(subject[:merge_request][:source_branch_path])
+
+          expect(subject[:merge_request][:target_branch])
+            .to eq(merge_request.target_branch)
+
+          expect(project_branch_path(project, merge_request.target_branch))
+            .to include(subject[:merge_request][:target_branch_path])
+        end
+      end
+
+      context 'when user is an external user' do
+        it 'has no merge request information' do
+          expect(subject[:merge_request]).to be_nil
+        end
+      end
+    end
   end
 end
diff --git a/spec/serializers/pipeline_serializer_spec.rb b/spec/serializers/pipeline_serializer_spec.rb
index 2bdcb2a45f6ecd252b9735210949ddd98457a877..a21487938a0f43da40e76eb981ebe43d9ef19824 100644
--- a/spec/serializers/pipeline_serializer_spec.rb
+++ b/spec/serializers/pipeline_serializer_spec.rb
@@ -97,6 +97,44 @@
       end
     end
 
+    context 'when there are pipelines for merge requests' do
+      let(:resource) { Ci::Pipeline.all }
+
+      let!(:merge_request_1) do
+        create(:merge_request,
+          :with_merge_request_pipeline,
+          target_project: project,
+          target_branch: 'master',
+          source_project: project,
+          source_branch: 'feature-1')
+      end
+
+      let!(:merge_request_2) do
+        create(:merge_request,
+          :with_merge_request_pipeline,
+          target_project: project,
+          target_branch: 'master',
+          source_project: project,
+          source_branch: 'feature-2')
+      end
+
+      before do
+        project.add_developer(user)
+      end
+
+      it 'includes merge requests information' do
+        expect(subject.all? { |entry| entry[:merge_request].present? }).to be_truthy
+      end
+
+      it 'preloads related merge requests', :postgresql do
+        recorded = ActiveRecord::QueryRecorder.new { subject }
+
+        expect(recorded.log)
+          .to include("SELECT \"merge_requests\".* FROM \"merge_requests\" " \
+                      "WHERE \"merge_requests\".\"id\" IN (#{merge_request_1.id}, #{merge_request_2.id})")
+      end
+    end
+
     describe 'number of queries when preloaded' do
       subject { serializer.represent(resource, preload: true) }
       let(:resource) { Ci::Pipeline.all }