diff --git a/ee/app/services/ai/duo_workflows/sanitize_job_variables_service.rb b/ee/app/services/ai/duo_workflows/sanitize_job_variables_service.rb
new file mode 100644
index 0000000000000000000000000000000000000000..a12ec8e76902abed108b491c07439dfab35b2ee4
--- /dev/null
+++ b/ee/app/services/ai/duo_workflows/sanitize_job_variables_service.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+module Ai
+  module DuoWorkflows
+    class SanitizeJobVariablesService
+      OVERRIDABLE_JOB_VARIABLES = {
+        GIT_DEPTH: 1
+      }.freeze
+
+      def initialize(dirty_variables)
+        @dirty_variables = (dirty_variables.presence || {}).symbolize_keys
+      end
+
+      def execute
+        invalid_variables = dirty_variables.keys - OVERRIDABLE_JOB_VARIABLES.keys
+
+        if invalid_variables.any?
+          return ServiceResponse.error(
+            message: <<~MESSAGE.squish,
+              Non-overridable variables detected: #{invalid_variables.to_sentence}.
+              Allowed variables: #{OVERRIDABLE_JOB_VARIABLES.keys.to_sentence}.
+            MESSAGE
+            reason: :unprocessable_entity)
+        end
+
+        sanitized_variables = OVERRIDABLE_JOB_VARIABLES.each_with_object({}) do |(key, value), variables|
+          variables[key] = dirty_variables.fetch(key, value)
+        end
+
+        ServiceResponse.success(payload: { variables: sanitized_variables })
+      end
+
+      private
+
+      attr_reader :dirty_variables
+    end
+  end
+end
diff --git a/ee/app/services/ai/duo_workflows/start_workflow_service.rb b/ee/app/services/ai/duo_workflows/start_workflow_service.rb
index 117e2003509841f056c8a4ca322a1065356d2832..cf017bcd37b22c77f42425f57a400bd0123b5e66 100644
--- a/ee/app/services/ai/duo_workflows/start_workflow_service.rb
+++ b/ee/app/services/ai/duo_workflows/start_workflow_service.rb
@@ -3,25 +3,19 @@
 module Ai
   module DuoWorkflows
     class StartWorkflowService
+      include ::Gitlab::Utils::StrongMemoize
+
       IMAGE = 'registry.gitlab.com/gitlab-org/duo-workflow/default-docker-image/workflow-generic-image:v0.0.4'
 
       def initialize(workflow:, params:)
         @workflow = workflow
         @current_user = workflow.user
         @params = params
+        @job_variables = (params.delete(:job_variables) || {}).symbolize_keys
       end
 
       def execute
-        unless @workflow.project_level?
-          return ServiceResponse.error(
-            message: 'Only project-level workflow is supported',
-            reason: :unprocessable_entity)
-        end
-
-        unless @current_user.can?(:execute_duo_workflow_in_ci, @workflow)
-          return ServiceResponse.error(message: 'Can not execute workflow in CI',
-            reason: :feature_unavailable)
-        end
+        return validation if validation.error?
 
         workload_user = @current_user
 
@@ -55,6 +49,33 @@ def execute
 
       private
 
+      def validation
+        sanitized_variables = ::Ai::DuoWorkflows::SanitizeJobVariablesService.new(@job_variables).execute
+
+        if sanitized_variables.error?
+          return ServiceResponse.error(
+            message: sanitized_variables.message,
+            reason: :unprocessable_entity)
+        end
+
+        unless @workflow.project_level?
+          return ServiceResponse.error(
+            message: 'Only project-level workflow is supported',
+            reason: :unprocessable_entity
+          )
+        end
+
+        unless @current_user.can?(:execute_duo_workflow_in_ci, @workflow)
+          return ServiceResponse.error(
+            message: 'Can not execute workflow in CI',
+            reason: :feature_unavailable
+          )
+        end
+
+        ServiceResponse.success
+      end
+      strong_memoize_attr :validation
+
       def workload_definition
         ::Ci::Workloads::WorkloadDefinition.new do |d|
           d.image = @workflow.image.presence || configured_image || IMAGE
@@ -86,6 +107,11 @@ def setup_script_commands
         duo_config.setup_script || []
       end
 
+      def sanitized_variables
+        ::Ai::DuoWorkflows::SanitizeJobVariablesService.new(@job_variables).execute
+      end
+      strong_memoize_attr :validation
+
       def variables
         {
           DUO_WORKFLOW_ADDITIONAL_CONTEXT_CONTENT: serialized_flow_additional_context,
@@ -110,7 +136,7 @@ def variables
           DUO_WORKFLOW_METADATA: @params[:workflow_metadata],
           GITLAB_BASE_URL: Gitlab.config.gitlab.url,
           AGENT_PLATFORM_GITLAB_VERSION: Gitlab.version_info.to_s
-        }
+        }.merge(sanitized_variables.payload.fetch(:variables))
       end
 
       def commands
diff --git a/ee/lib/api/ai/duo_workflows/workflows.rb b/ee/lib/api/ai/duo_workflows/workflows.rb
index 9174dc193bd0bd8983b27f5d4df9a0a990a6aad1..e5f22aa37e929db14c4be4ba01be8e0eb86b79fa 100644
--- a/ee/lib/api/ai/duo_workflows/workflows.rb
+++ b/ee/lib/api/ai/duo_workflows/workflows.rb
@@ -17,6 +17,8 @@ class Workflows < ::API::Base
         end
 
         helpers do
+          include Gitlab::Utils::StrongMemoize
+
           def find_root_namespace
             # The IDE sends namespace data via the header, while the web agentic chat UI
             # sends it as a query param.
@@ -78,7 +80,8 @@ def start_workflow_params(workflow_id)
               use_service_account: token_service.use_service_account?,
               source_branch: params[:source_branch],
               additional_context: params[:additional_context],
-              workflow_metadata: Gitlab::DuoWorkflow::Client.metadata(current_user).to_json
+              workflow_metadata: Gitlab::DuoWorkflow::Client.metadata(current_user).to_json,
+              job_variables: sanitized_variables.payload.fetch(:variables)
             }
           end
 
@@ -121,8 +124,13 @@ def duo_workflow_list_tools
           end
 
           def create_workflow_params
-            wrkf_params = declared_params(include_missing: false).except(:start_workflow, :source_branch,
-              :additional_context)
+            wrkf_params = declared_params(include_missing: false).except(
+              :start_workflow,
+              :source_branch,
+              :additional_context,
+              :job_variables
+            )
+
             return wrkf_params unless wrkf_params[:ai_catalog_item_version_id]
 
             wrkf_params[:ai_catalog_item_version] = ::Ai::Catalog::ItemVersion
@@ -130,6 +138,11 @@ def create_workflow_params
             wrkf_params
           end
 
+          def sanitized_variables
+            ::Ai::DuoWorkflows::SanitizeJobVariablesService.new(params[:job_variables]).execute
+          end
+          strong_memoize_attr :sanitized_variables
+
           params :workflow_params do
             optional :project_id, type: String, desc: 'The ID or path of the workflow project',
               documentation: { example: '1' }
@@ -179,6 +192,9 @@ def create_workflow_params
                 example: '[{"Category": "agent_user_environment", "Content": "{\"merge_request_url\": ' \
                   'https://gitlab.com/project/-/merge_requests/1\"}", "Metadata": "{}"}]'
               }
+            optional :job_variables, type: Hash,
+              desc: 'Overridable environment variables to pass to the workflow job.',
+              documentation: { example: '{"GIT_DEPTH": 30}' }
             exactly_one_of :project_id, :namespace_id
           end
         end
@@ -317,6 +333,8 @@ def create_workflow_params
                   'https://gitlab.com/gitlab-org/gitlab/-/issues/566195', new_threshold: 105
                 )
 
+                bad_request!(sanitized_variables.message) if sanitized_variables.error?
+
                 container = if params[:project_id]
                               find_project!(params[:project_id])
                             elsif params[:namespace_id]
diff --git a/ee/spec/requests/api/ai/duo_workflows/workflows_spec.rb b/ee/spec/requests/api/ai/duo_workflows/workflows_spec.rb
index fc4975b28a10c8e805602054bbcad03b4594b6c0..0bad54378180e418d4a27955aaa7171efa853e73 100644
--- a/ee/spec/requests/api/ai/duo_workflows/workflows_spec.rb
+++ b/ee/spec/requests/api/ai/duo_workflows/workflows_spec.rb
@@ -573,6 +573,46 @@
           expect(response).to have_gitlab_http_status(:bad_request)
         end
       end
+
+      context 'when valid job_variables are provided' do
+        let(:job_variables) do
+          { 'GIT_DEPTH' => '15' }
+        end
+
+        let(:params) do
+          super().merge(job_variables: job_variables)
+        end
+
+        it 'passes job_variables to StartWorkflowService' do
+          expect(::Ai::DuoWorkflows::StartWorkflowService).to receive(:new).with(
+            workflow: anything,
+            params: hash_including(job_variables: { GIT_DEPTH: '15' })
+          ).and_call_original
+
+          post api(path, user), params: params
+
+          expect(response).to have_gitlab_http_status(:created)
+        end
+      end
+
+      context 'when invalid job_variables are provided' do
+        let(:job_variables) do
+          { 'GIT_STRATEGY' => 'fetch' }
+        end
+
+        let(:params) do
+          super().merge(job_variables: job_variables)
+        end
+
+        it 'returns an API error' do
+          post api(path, user), params: params
+
+          expect(response).to have_gitlab_http_status(:bad_request)
+          expect(response.body).to include(
+            'Non-overridable variables detected: GIT_STRATEGY. Allowed variables: GIT_DEPTH'
+          )
+        end
+      end
     end
   end
 
diff --git a/ee/spec/services/ai/duo_workflows/sanitize_job_variables_service_spec.rb b/ee/spec/services/ai/duo_workflows/sanitize_job_variables_service_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..047a655a33dafafba42a1a40b7ee7e3c9ca3a2d6
--- /dev/null
+++ b/ee/spec/services/ai/duo_workflows/sanitize_job_variables_service_spec.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Ai::DuoWorkflows::SanitizeJobVariablesService, feature_category: :agent_foundations do
+  subject(:result) { described_class.new(dirty_variables).execute }
+
+  let(:variables) { result.payload.fetch(:variables) }
+  let(:default_values) { described_class::OVERRIDABLE_JOB_VARIABLES }
+
+  context 'when dirty variables are invalid' do
+    let(:dirty_variables) { { GIT_STRATEGY: 'fetch' } }
+
+    it 'returns an error' do
+      expect(result).to be_error
+      expect(result.message).to eq('Non-overridable variables detected: GIT_STRATEGY. Allowed variables: GIT_DEPTH.')
+    end
+  end
+
+  context 'when dirty variables are valid' do
+    let(:dirty_variables) { { GIT_DEPTH: 15 } }
+
+    it 'returns the sanitized variables' do
+      expect(result).to be_success
+      expect(variables).to eq(GIT_DEPTH: 15)
+    end
+  end
+
+  context 'when dirty variables keys are string' do
+    let(:dirty_variables) { { 'GIT_DEPTH' => 15 } }
+
+    it 'sanitize keys to symbols' do
+      expect(result).to be_success
+      expect(variables).to eq(GIT_DEPTH: 15)
+    end
+  end
+
+  context 'when dirty variables are nil' do
+    let(:dirty_variables) { nil }
+
+    it 'returns the default values' do
+      expect(result).to be_success
+      expect(variables).to eq(default_values)
+    end
+  end
+
+  context 'when dirty variables are empty' do
+    let(:dirty_variables) { {} }
+
+    it 'returns the default values' do
+      expect(result).to be_success
+      expect(variables).to eq(default_values)
+    end
+  end
+end
diff --git a/ee/spec/services/ai/duo_workflows/start_workflow_service_spec.rb b/ee/spec/services/ai/duo_workflows/start_workflow_service_spec.rb
index 0290ee3a7fdf1bd24ba947074346caf04fd64977..d9621378a47df0a258b4d28592359c3470a69ba1 100644
--- a/ee/spec/services/ai/duo_workflows/start_workflow_service_spec.rb
+++ b/ee/spec/services/ai/duo_workflows/start_workflow_service_spec.rb
@@ -170,6 +170,13 @@
     end
   end
 
+  shared_context 'with Duo enabled' do
+    before do
+      allow(::Gitlab::Llm::StageCheck).to receive(:available?).with(project, :duo_workflow).and_return(true)
+      allow(maintainer).to receive(:allowed_to_use?).and_return(true)
+    end
+  end
+
   subject(:execute) { described_class.new(workflow: workflow, params: params).execute }
 
   context 'with workflow enablement checks' do
@@ -787,4 +794,59 @@
       end
     end
   end
+
+  context 'without custom job variables', :aggregate_failures do
+    include_context 'with Duo enabled'
+
+    it 'uses default variables' do
+      expect(Ci::Workloads::RunWorkloadService).to receive(:new).and_wrap_original do |method, **kwargs|
+        workload_definition = kwargs[:workload_definition]
+        variables = workload_definition.variables
+
+        expect(variables[:GIT_DEPTH]).to eq(1)
+
+        method.call(**kwargs)
+      end
+
+      expect(execute).to be_success
+    end
+  end
+
+  context 'with valid custom job variables' do
+    include_context 'with Duo enabled'
+
+    let(:params) do
+      super().merge(job_variables: { 'GIT_DEPTH' => 15 })
+    end
+
+    it 'merges with default variables' do
+      expect(Ci::Workloads::RunWorkloadService).to receive(:new).and_wrap_original do |method, **kwargs|
+        workload_definition = kwargs[:workload_definition]
+        variables = workload_definition.variables
+
+        expect(variables[:GIT_DEPTH]).to eq(15)
+
+        method.call(**kwargs)
+      end
+
+      expect(execute).to be_success
+    end
+  end
+
+  context 'with invalid custom job variables' do
+    include_context 'with Duo enabled'
+
+    let(:params) do
+      super().merge(job_variables: { 'GIT_DEPTH' => 15, 'GIT_STRATEGY' => 'fetch', 'FOO' => 'bar' })
+    end
+
+    it 'does not create a workflow' do
+      expect(execute).to be_error
+      expect(execute.reason).to eq(:unprocessable_entity)
+      expect(execute.message).to eq(<<~MESSAGE.squish)
+        Non-overridable variables detected: GIT_STRATEGY and FOO.
+        Allowed variables: GIT_DEPTH.
+      MESSAGE
+    end
+  end
 end