diff --git a/changelogs/unreleased/api-issuable-bulk-update.yml b/changelogs/unreleased/api-issuable-bulk-update.yml
new file mode 100644
index 00000000000..3d4e96f9d1b
--- /dev/null
+++ b/changelogs/unreleased/api-issuable-bulk-update.yml
@@ -0,0 +1,5 @@
+---
+title: 'API: Bulk update for issues and MRs'
+merge_request: 25201
+author: Robert Schilling
+type: added
diff --git a/doc/api/issues.md b/doc/api/issues.md
index 0571f280d2a..27ae54da316 100644
--- a/doc/api/issues.md
+++ b/doc/api/issues.md
@@ -639,6 +639,37 @@ Example response:
 
 **Note**: The `closed_by` attribute was [introduced in GitLab 10.6][ce-17042]. This value will only be present for issues which were closed after GitLab 10.6 and when the user account that closed the issue still exists.
 
+## Bulk update issues
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21368) in GitLab 11.9.
+
+Update multiple issues using a single API call. Returns the number of successfully updated issues.
+
+```
+PUT /projects/:id/issues/bulk_update
+```
+
+| Attribute      | Type    | Required | Description                                                                                          ****      |
+|----------------|---------|----------|------------------------------------------------------------------------------------------------------------|
+| `id`           | integer/string | yes      | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding) owned by the authenticated user. |
+| `issuable_ids`  | Array[integer] | yes     | The IDs of issues to be updated.                                                                       |
+| `assignee_ids`  | Array[integer] | no      | The ID of the user(s) to assign the issue to. Set to `0` or provide an empty value to unassign all assignees.  |
+| `milestone_id`  | integer        | no      | The global ID of a milestone to assign the issue to. Set to `0` or provide an empty value to unassign a milestone.|
+| `add_label_ids`      | Array[integer] | no | Comma-separated label IDs to be added. |
+| `remove_label_ids`   | Array[integer] | no | Comma-separated label IDs to be added. |
+| `state_event`        | string  | no  | The state event of an issue. Set `close` to close the issue and `reopen` to reopen it.                      |
+| `subscription_event` | string  | no  | The subscription_event event of an issue. Set `subscribe` to subscribe to the issue and `unsubscribe` to unsubscribe from it. |
+
+```bash
+curl --request PUT --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/projects/4/issues/bulk_update?issuable_ids[]=1&issuable_ids[]=2&state_event=close
+```
+
+Example response:
+
+```json
+{ "message": "2 issues updated" }
+```
+
 ## Delete an issue
 
 Only for admins and project owners. Soft deletes the issue in question.
diff --git a/doc/api/merge_requests.md b/doc/api/merge_requests.md
index e176cdffc5f..ba47e507b79 100644
--- a/doc/api/merge_requests.md
+++ b/doc/api/merge_requests.md
@@ -956,6 +956,37 @@ Must include at least one non-required attribute from above.
 }
 ```
 
+## Bulk update merge requests
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21368) in GitLab 11.9.
+
+Update multiple merge requests using a single API call. Returns the number of successfully updated merge requests.
+
+```
+PUT /projects/:id/merge_requests/bulk_update
+```
+
+| Attribute      | Type    | Required | Description                                                                                          ****      |
+|----------------|---------|----------|------------------------------------------------------------------------------------------------------------|
+| `id`           | integer/string | yes      | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding) owned by the authenticated user. |
+| `issuable_ids`  | Array[integer] | yes     | The IDs of merge requests to be updated.                                                                       |
+| `assignee_ids`  | Array[integer] | no      | The ID of the user(s) to assign the issue to. Set to `0` or provide an empty value to unassign all assignees.  |
+| `milestone_id`  | integer        | no      | The global ID of a milestone to assign the issue to. Set to `0` or provide an empty value to unassign a milestone.|
+| `add_label_ids`      | Array[integer] | no | Comma-separated label IDs to be added. |
+| `remove_label_ids`   | Array[integer] | no | Comma-separated label IDs to be added. |
+| `state_event`        | string  | no  | The state event of an issue. Set `close` to close the issue and `reopen` to reopen it.                      |
+| `subscription_event` | string  | no  | The subscription_event event of an issue. Set `subscribe` to subscribe to the issue and `unsubscribe` to unsubscribe from it. |
+
+```bash
+curl --request PUT --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/projects/4/merge_requests/bulk_update?issuable_ids[]=1&issuable_ids[]=2&state_event=close
+```
+
+Example response:
+
+```json
+{ "message": "2 merge_requests updated" }
+```
+
 ## Delete a merge request
 
 Only for admins and project owners. Soft deletes the merge request in question.
diff --git a/lib/api/api.rb b/lib/api/api.rb
index 4dd1b459554..3bcf5150b43 100644
--- a/lib/api/api.rb
+++ b/lib/api/api.rb
@@ -115,6 +115,7 @@ module API
     mount ::API::GroupVariables
     mount ::API::ImportGithub
     mount ::API::Internal
+    mount ::API::IssuableBulkUpdate
     mount ::API::Issues
     mount ::API::JobArtifacts
     mount ::API::Jobs
diff --git a/lib/api/issuable_bulk_update.rb b/lib/api/issuable_bulk_update.rb
new file mode 100644
index 00000000000..5ac6c252d96
--- /dev/null
+++ b/lib/api/issuable_bulk_update.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module API
+  class IssuableBulkUpdate < Grape::API
+    params do
+      requires :id, type: String, desc: 'The ID of a project'
+    end
+    resource :projects, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+      %w(issue merge_request).each do |issuable|
+        desc "Updates a list of #{issuable.pluralize}" do
+          detail 'This feature was introduced in 11.9'
+        end
+        params do
+          requires :issuable_ids, type: Array[Integer], desc: "Array of #{issuable.pluralize} IDs to be updated"
+          optional :state_event, type: String, values: %w(reopen close), desc: 'Reopens or closes a resource'
+          optional :milestone_id, type: Integer, desc: 'The milestone ID number'
+          optional :add_label_ids, type: Array[Integer], desc: 'IDs of labels to be added'
+          optional :remove_label_ids, type: Array[Integer], desc: 'IDs of labels to be removed'
+          optional :subscription_event, type: String, values: %w(subscribe unsubscribe),
+                                        desc: 'Subscribes or unsubscribes from a resource'
+
+          if issuable == 'issue'
+            optional :assignee_ids, type: Array[Integer], desc: 'List of assignee IDs'
+            at_least_one_of :state_event, :milestone_id, :add_label_ids, :remove_label_ids,
+                            :subscription_event, :assignee_ids
+          else
+            optional :assignee_id, type: Integer, desc: 'ID of the assignee'
+            at_least_one_of :state_event, :milestone_id, :add_label_ids, :remove_label_ids,
+                            :subscription_event, :assignee_id
+          end
+        end
+        put ":id/#{issuable.pluralize}/bulk_update" do
+          authorize! :"admin_#{issuable}", user_project
+
+          update_params = declared_params(include_missing: false)
+
+          result = Issuable::BulkUpdateService.new(user_project, current_user, update_params)
+            .execute(issuable)
+
+          if result[:success]
+            status 200
+            quantity = result[:count]
+            { message: "#{quantity} #{issuable.pluralize(quantity)} updated" }
+          else
+            render_api_error!('Bulk update failed', 400)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/requests/api/issuable_bulk_update_spec.rb b/spec/requests/api/issuable_bulk_update_spec.rb
new file mode 100644
index 00000000000..6463f3f5d35
--- /dev/null
+++ b/spec/requests/api/issuable_bulk_update_spec.rb
@@ -0,0 +1,154 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe API::IssuableBulkUpdate do
+  set(:project) { create(:project) }
+  set(:user) { project.creator }
+
+  shared_examples "PUT /projects/:id/:issuable/bulk_update" do |issuable|
+    def bulk_update(issuable, issuables, params, update_user = user)
+      put api("/projects/#{project.id}/#{issuable.pluralize}/bulk_update", update_user),
+        params: { issuable_ids: Array(issuables).map(&:id) }.merge(params)
+    end
+
+    context 'with not enough permissions' do
+      it 'returns 403 for guest users' do
+        guest = create(:user)
+        project.add_guest(guest)
+
+        bulk_update(issuable, issuables, { state_event: 'close' }, guest)
+
+        expect(response).to have_gitlab_http_status(403)
+      end
+    end
+
+    context 'when modifying the state' do
+      it "closes #{issuable}" do
+        bulk_update(issuable, issuables, { state_event: 'close' })
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response['message']).to eq("#{issuables.count} #{issuable.pluralize(issuables.count)} updated")
+        expect(project.public_send(issuable.pluralize).opened).to be_empty
+        expect(project.public_send(issuable.pluralize).closed).not_to be_empty
+      end
+
+      it "opens #{issuable}" do
+        closed_issuables = create_list("closed_#{issuable}".to_sym, 2)
+
+        bulk_update(issuable, closed_issuables, { state_event: 'reopen' })
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(project.public_send(issuable.pluralize).closed).to be_empty
+      end
+    end
+
+    context 'when modifying the milestone' do
+      let(:milestone) { create(:milestone, project: project) }
+
+      it "adds a milestone #{issuable}" do
+        bulk_update(issuable, issuables, { milestone_id: milestone.id })
+
+        expect(response).to have_gitlab_http_status(200)
+        issuables.each do |issuable|
+          expect(issuable.reload.milestone).to eq(milestone)
+        end
+      end
+
+      it 'removes a milestone' do
+        issuables.first.milestone = milestone
+        milestone_issuable = issuables.first
+
+        bulk_update(issuable, [milestone_issuable], { milestone_id: 0 })
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(milestone_issuable.reload.milestone).to eq(nil)
+      end
+    end
+
+    context 'when modifying the subscription state' do
+      it "subscribes to #{issuable}" do
+        bulk_update(issuable, issuables, { subscription_event: 'subscribe' })
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(issuables).to all(be_subscribed(user, project))
+      end
+
+      it 'unsubscribes from issues' do
+        issuables.each do |issuable|
+          issuable.subscriptions.create(user: user, project: project, subscribed: true)
+        end
+
+        bulk_update(issuable, issuables, { subscription_event: 'unsubscribe' })
+
+        expect(response).to have_gitlab_http_status(200)
+        issuables.each do |issuable|
+          expect(issuable).not_to be_subscribed(user, project)
+        end
+      end
+    end
+
+    context 'when modifying the assignee' do
+      it 'adds assignee to issues' do
+        params = issuable == 'issue' ? { assignee_ids: [user.id] } : { assignee_id: user.id }
+
+        bulk_update(issuable, issuables, params)
+
+        expect(response).to have_gitlab_http_status(200)
+        issuables.each do |issuable|
+          expect(issuable.reload.assignees).to eq([user])
+        end
+      end
+
+      it 'removes assignee' do
+        assigned_issuable = issuables.first
+
+        if issuable == 'issue'
+          params = { assignee_ids: 0 }
+          assigned_issuable.assignees << user
+        else
+          params = { assignee_id: 0 }
+          assigned_issuable.update_attribute(:assignee, user)
+        end
+
+        bulk_update(issuable, [assigned_issuable], params)
+        expect(assigned_issuable.reload.assignees).to eq([])
+      end
+    end
+
+    context 'when modifying labels' do
+      let(:bug) { create(:label, project: project) }
+      let(:regression) { create(:label, project: project) }
+      let(:feature) { create(:label, project: project) }
+
+      it 'adds new labels' do
+        bulk_update(issuable, issuables, { add_label_ids: [bug.id, regression.id, feature.id] })
+
+        issuables.each do |issusable|
+          expect(issusable.reload.label_ids).to contain_exactly(bug.id, regression.id, feature.id)
+        end
+      end
+
+      it 'removes labels' do
+        labled_issuable = issuables.first
+        labled_issuable.labels << bug
+        labled_issuable.labels << regression
+        labled_issuable.labels << feature
+
+        bulk_update(issuable, [labled_issuable], { remove_label_ids: [bug.id, regression.id] })
+
+        expect(labled_issuable.reload.label_ids).to contain_exactly(feature.id)
+      end
+    end
+  end
+
+  it_behaves_like 'PUT /projects/:id/:issuable/bulk_update', 'issue' do
+    let(:issuables) { create_list(:issue, 2, project: project) }
+  end
+
+  it_behaves_like 'PUT /projects/:id/:issuable/bulk_update', 'merge_request' do
+    let(:merge_request_1) { create(:merge_request, source_project: project) }
+    let(:merge_request_2) { create(:merge_request, :simple, source_project: project) }
+    let(:issuables) { [merge_request_1, merge_request_2] }
+  end
+end