diff --git a/config/routes/project.rb b/config/routes/project.rb
index 00d674575c4991b0bc4e34ec87bc1649ee310ca2..078fa15e40f1f09f4c2fea283fbacbf1f771eac9 100644
--- a/config/routes/project.rb
+++ b/config/routes/project.rb
@@ -1,10 +1,12 @@
 # frozen_string_literal: true
 
+# rubocop: disable Cop/PutProjectRoutesUnderScope
 resources :projects, only: [:index, :new, :create]
 
 draw :git_http
 
 get '/projects/:id' => 'projects#resolve'
+# rubocop: enable Cop/PutProjectRoutesUnderScope
 
 constraints(::Constraints::ProjectUrlConstrainer.new) do
   # If the route has a wildcard segment, the segment has a regex constraint,
@@ -210,6 +212,10 @@
       end
       # End of the /-/ scope.
 
+      # All new routes should go under /-/ scope.
+      # Look for scope '-' at the top of the file.
+      # rubocop: disable Cop/PutProjectRoutesUnderScope
+
       #
       # Templates
       #
@@ -524,6 +530,10 @@
       draw :wiki
       draw :repository
 
+      # All new routes should go under /-/ scope.
+      # Look for scope '-' at the top of the file.
+      # rubocop: enable Cop/PutProjectRoutesUnderScope
+
       # Legacy routes.
       # Introduced in 12.0.
       # Should be removed with https://gitlab.com/gitlab-org/gitlab/issues/28848.
@@ -535,6 +545,7 @@
                                             :cycle_analytics, :mattermost, :variables, :triggers)
     end
 
+    # rubocop: disable Cop/PutProjectRoutesUnderScope
     resources(:projects,
               path: '/',
               constraints: { id: Gitlab::PathRegex.project_route_regex },
@@ -556,5 +567,6 @@
         put :new_issuable_address
       end
     end
+    # rubocop: enable Cop/PutProjectRoutesUnderScope
   end
 end
diff --git a/ee/config/routes/project.rb b/ee/config/routes/project.rb
index 9d0cc6e8c3743653c593943e23271d57932ed0a0..8c84cfd64a0fb801a94f32b02fe1236790e643df 100644
--- a/ee/config/routes/project.rb
+++ b/ee/config/routes/project.rb
@@ -64,6 +64,10 @@
       end
       # End of the /-/ scope.
 
+      # All new routes should go under /-/ scope.
+      # Look for scope '-' at the top of the file.
+      # rubocop: disable Cop/PutProjectRoutesUnderScope
+
       resources :path_locks, only: [:index, :destroy] do
         collection do
           post :toggle
@@ -206,6 +210,10 @@
       end
 
       resources :audit_events, only: [:index]
+
+      # All new routes should go under /-/ scope.
+      # Look for scope '-' at the top of the file.
+      # rubocop: enable Cop/PutProjectRoutesUnderScope
     end
   end
 end
diff --git a/rubocop/cop/put_project_routes_under_scope.rb b/rubocop/cop/put_project_routes_under_scope.rb
new file mode 100644
index 0000000000000000000000000000000000000000..02189f43ea03d0b8d5e1f00987ebe3afceb8082a
--- /dev/null
+++ b/rubocop/cop/put_project_routes_under_scope.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    # Checks for a project routes outside '/-/' scope.
+    # For more information see: https://gitlab.com/gitlab-org/gitlab/issues/29572
+    class PutProjectRoutesUnderScope < RuboCop::Cop::Cop
+      MSG = 'Put new project routes under /-/ scope'
+
+      def_node_matcher :dash_scope?, <<~PATTERN
+        (:send nil? :scope (:str "-"))
+      PATTERN
+
+      def on_send(node)
+        return unless in_project_routes?(node)
+        return unless resource?(node)
+        return unless outside_scope?(node)
+
+        add_offense(node)
+      end
+
+      def outside_scope?(node)
+        node.each_ancestor(:block).none? do |parent|
+          dash_scope?(parent.to_a.first)
+        end
+      end
+
+      def in_project_routes?(node)
+        path = node.location.expression.source_buffer.name
+        dirname = File.dirname(path)
+        filename = File.basename(path)
+
+        dirname.end_with?('config/routes') &&
+          filename.end_with?('project.rb')
+      end
+
+      def resource?(node)
+        node.method_name == :resource ||
+          node.method_name == :resources
+      end
+    end
+  end
+end
diff --git a/rubocop/rubocop.rb b/rubocop/rubocop.rb
index 159892ae0c1ea510f47c939337a9e532a65fab50..49d582bf034f9aeed79e00d004d2ad427c299b89 100644
--- a/rubocop/rubocop.rb
+++ b/rubocop/rubocop.rb
@@ -14,6 +14,7 @@
 require_relative 'cop/avoid_route_redirect_leading_slash'
 require_relative 'cop/line_break_around_conditional_block'
 require_relative 'cop/prefer_class_methods_over_module'
+require_relative 'cop/put_project_routes_under_scope'
 require_relative 'cop/migration/add_column'
 require_relative 'cop/migration/add_concurrent_foreign_key'
 require_relative 'cop/migration/add_concurrent_index'
diff --git a/spec/rubocop/cop/put_project_routes_under_scope_spec.rb b/spec/rubocop/cop/put_project_routes_under_scope_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..b0f1e52f3972d6b51199c6b4972c21778a1bae62
--- /dev/null
+++ b/spec/rubocop/cop/put_project_routes_under_scope_spec.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'rubocop'
+require_relative '../../../rubocop/cop/put_project_routes_under_scope'
+
+describe RuboCop::Cop::PutProjectRoutesUnderScope do
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+
+  before do
+    allow(cop).to receive(:in_project_routes?).and_return(true)
+  end
+
+  it 'registers an offense when route is outside scope' do
+    expect_offense(<<~PATTERN.strip_indent)
+      scope '-' do
+        resource :issues
+      end
+
+      resource :notes
+      ^^^^^^^^^^^^^^^ Put new project routes under /-/ scope
+    PATTERN
+  end
+
+  it 'does not register an offense when resource inside the scope' do
+    expect_no_offenses(<<~PATTERN.strip_indent)
+      scope '-' do
+        resource :issues
+        resource :notes
+      end
+    PATTERN
+  end
+
+  it 'does not register an offense when resource is deep inside the scope' do
+    expect_no_offenses(<<~PATTERN.strip_indent)
+      scope '-' do
+        resource :issues
+        resource :projects do
+          resource :issues do
+            resource :notes
+          end
+        end
+      end
+    PATTERN
+  end
+end