diff --git a/changelogs/unreleased/fix-gb-update-commit-status-api.yml b/changelogs/unreleased/fix-gb-update-commit-status-api.yml
new file mode 100644
index 00000000000..aa4fcba4e89
--- /dev/null
+++ b/changelogs/unreleased/fix-gb-update-commit-status-api.yml
@@ -0,0 +1,4 @@
+---
+title: Fix updaing commit status when using optional attributes
+merge_request: 9618
+author:
diff --git a/lib/api/commit_statuses.rb b/lib/api/commit_statuses.rb
index dba0831664c..9d9f82fdb83 100644
--- a/lib/api/commit_statuses.rb
+++ b/lib/api/commit_statuses.rb
@@ -72,14 +72,15 @@ module API
         status = GenericCommitStatus.running_or_pending.find_or_initialize_by(
           project: @project,
           pipeline: pipeline,
-          user: current_user,
           name: name,
           ref: ref,
-          target_url: params[:target_url],
-          description: params[:description],
-          coverage: params[:coverage]
+          user: current_user
         )
 
+        optional_attributes =
+          attributes_for_keys(%w[target_url description coverage])
+
+        status.update(optional_attributes) if optional_attributes.any?
         render_validation_error!(status) if status.invalid?
 
         begin
diff --git a/spec/requests/api/commit_statuses_spec.rb b/spec/requests/api/commit_statuses_spec.rb
index 81a8856b8f1..d8b3cc041a5 100644
--- a/spec/requests/api/commit_statuses_spec.rb
+++ b/spec/requests/api/commit_statuses_spec.rb
@@ -151,26 +151,62 @@ describe API::CommitStatuses, api: true do
       end
 
       context 'with all optional parameters' do
-        before do
-          optional_params = { state: 'success',
-                              context: 'coverage',
-                              ref: 'develop',
-                              description: 'test',
-                              coverage: 80.0,
-                              target_url: 'http://gitlab.com/status' }
+        context 'when creating a commit status' do
+          it 'creates commit status' do
+            post api(post_url, developer), {
+              state: 'success',
+              context: 'coverage',
+              ref: 'develop',
+              description: 'test',
+              coverage: 80.0,
+              target_url: 'http://gitlab.com/status'
+            }
 
-          post api(post_url, developer), optional_params
+            expect(response).to have_http_status(201)
+            expect(json_response['sha']).to eq(commit.id)
+            expect(json_response['status']).to eq('success')
+            expect(json_response['name']).to eq('coverage')
+            expect(json_response['ref']).to eq('develop')
+            expect(json_response['coverage']).to eq(80.0)
+            expect(json_response['description']).to eq('test')
+            expect(json_response['target_url']).to eq('http://gitlab.com/status')
+          end
         end
 
-        it 'creates commit status' do
-          expect(response).to have_http_status(201)
-          expect(json_response['sha']).to eq(commit.id)
-          expect(json_response['status']).to eq('success')
-          expect(json_response['name']).to eq('coverage')
-          expect(json_response['ref']).to eq('develop')
-          expect(json_response['coverage']).to eq(80.0)
-          expect(json_response['description']).to eq('test')
-          expect(json_response['target_url']).to eq('http://gitlab.com/status')
+        context 'when updatig a commit status' do
+          before do
+            post api(post_url, developer), {
+              state: 'running',
+              context: 'coverage',
+              ref: 'develop',
+              description: 'coverage test',
+              coverage: 0.0,
+              target_url: 'http://gitlab.com/status'
+            }
+
+            post api(post_url, developer), {
+              state: 'success',
+              name: 'coverage',
+              ref: 'develop',
+              description: 'new description',
+              coverage: 90.0
+            }
+          end
+
+          it 'updates a commit status' do
+            expect(response).to have_http_status(201)
+            expect(json_response['sha']).to eq(commit.id)
+            expect(json_response['status']).to eq('success')
+            expect(json_response['name']).to eq('coverage')
+            expect(json_response['ref']).to eq('develop')
+            expect(json_response['coverage']).to eq(90.0)
+            expect(json_response['description']).to eq('new description')
+            expect(json_response['target_url']).to eq('http://gitlab.com/status')
+          end
+
+          it 'does not create a new commit status' do
+            expect(CommitStatus.count).to eq 1
+          end
         end
       end