diff --git a/changelog/fix_enforce_gem_file_name.md b/changelog/fix_enforce_gem_file_name.md
new file mode 100644
index 00000000000..0466e6e1aa9
--- /dev/null
+++ b/changelog/fix_enforce_gem_file_name.md
@@ -0,0 +1 @@
+* [#9580](https://github.com/rubocop/rubocop/issues/9580): Add a new cop that enforces which bundler gem file to use. ([@gregfletch][])
diff --git a/config/default.yml b/config/default.yml
index 53e201581c4..780410b1ae2 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -174,6 +174,12 @@ Bundler/GemComment:
   IgnoredGems: []
   OnlyFor: []
 
+Bundler/GemFilename:
+  Description: 'Enforces the filename for managing gems.'
+  Enabled: true
+  VersionAdded: '<<next>>'
+  RequiresGemfile: true
+
 Bundler/GemVersion:
   Description: 'Requires or forbids specifying gem versions.'
   Enabled: false
diff --git a/lib/rubocop.rb b/lib/rubocop.rb
index 7dc7b4dcc06..ad2799d3ed3 100644
--- a/lib/rubocop.rb
+++ b/lib/rubocop.rb
@@ -152,6 +152,7 @@
 
 require_relative 'rubocop/cop/bundler/duplicated_gem'
 require_relative 'rubocop/cop/bundler/gem_comment'
+require_relative 'rubocop/cop/bundler/gem_filename'
 require_relative 'rubocop/cop/bundler/gem_version'
 require_relative 'rubocop/cop/bundler/insecure_protocol_source'
 require_relative 'rubocop/cop/bundler/ordered_gems'
diff --git a/lib/rubocop/cop/bundler/gem_filename.rb b/lib/rubocop/cop/bundler/gem_filename.rb
new file mode 100644
index 00000000000..68e187c1256
--- /dev/null
+++ b/lib/rubocop/cop/bundler/gem_filename.rb
@@ -0,0 +1,90 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Bundler
+      # This cop verifies that a project contains Gemfile or gems.rb file and correct
+      # associated lock file based on the configuration.
+      #
+      # @example RequiresGemfile: true (default)
+      #   # bad
+      #   Project contains gems.rb and gems.locked files
+      #
+      #   # bad
+      #   Project contains Gemfile and gems.locked file
+      #
+      #   # good
+      #   Project contains Gemfile and Gemfile.lock
+      #
+      # @example RequiresGemfile: false
+      #   # bad
+      #   Project contains Gemfile and Gemfile.lock files
+      #
+      #   # bad
+      #   Project contains gems.rb and Gemfile.lock file
+      #
+      #   # good
+      #   Project contains gems.rb and gems.locked files
+      class GemFilename < Base
+        include RangeHelp
+
+        MSG_GEMFILE_REQUIRED = 'gems.rb file was found but Gemfile is required.'
+        MSG_GEMS_RB_REQUIRED = 'Gemfile was found but gems.rb file is required.'
+        MSG_GEMFILE_MISMATCHED = 'Expected a Gemfile.lock with Gemfile but found gems.locked file.'
+        MSG_GEMS_RB_MISMATCHED = 'Expected a gems.locked file with gems.rb but found Gemfile.lock.'
+        GEMFILE_REQUIRED_CONFIG = 'RequiresGemfile'
+        GEMFILE_FILES = %w[Gemfile Gemfile.lock].freeze
+        GEMS_RB_FILES = %w[gems.rb gems.locked].freeze
+
+        def on_new_investigation
+          file_path = processed_source.file_path
+          return if expected_gemfile?(file_path)
+
+          register_offense(processed_source, file_path)
+        end
+
+        private
+
+        def register_offense(processed_source, file_path)
+          register_gemfile_offense(processed_source, file_path) if gemfile_required?
+          register_gems_rb_offense(processed_source, file_path) unless gemfile_required?
+        end
+
+        def register_gemfile_offense(processed_source, file_path)
+          message = case file_path
+                    when 'gems.rb'
+                      MSG_GEMFILE_REQUIRED
+                    when 'gems.locked'
+                      MSG_GEMFILE_MISMATCHED
+                    end
+
+          return if message.nil?
+
+          add_offense(source_range(processed_source.buffer, 1, 0), message: message)
+        end
+
+        def register_gems_rb_offense(processed_source, file_path)
+          message = case file_path
+                    when 'Gemfile'
+                      MSG_GEMS_RB_REQUIRED
+                    when 'Gemfile.lock'
+                      MSG_GEMS_RB_MISMATCHED
+                    end
+
+          return if message.nil?
+
+          add_offense(source_range(processed_source.buffer, 1, 0), message: message)
+        end
+
+        def expected_gemfile?(file_path)
+          (gemfile_required? && GEMFILE_FILES.include?(file_path)) ||
+            (!gemfile_required? && GEMS_RB_FILES.include?(file_path))
+        end
+
+        def gemfile_required?
+          cop_config[GEMFILE_REQUIRED_CONFIG]
+        end
+      end
+    end
+  end
+end
diff --git a/spec/rubocop/cop/bundler/gem_filename_spec.rb b/spec/rubocop/cop/bundler/gem_filename_spec.rb
new file mode 100644
index 00000000000..5508f7c297b
--- /dev/null
+++ b/spec/rubocop/cop/bundler/gem_filename_spec.rb
@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Bundler::GemFilename, :config do
+  shared_examples_for 'invalid gem file' do |message|
+    it 'registers an offense' do
+      offenses = _investigate(cop, processed_source)
+
+      expect(offenses.size).to eq(1)
+      expect(offenses.first.message).to eq(message)
+    end
+  end
+
+  shared_examples_for 'valid gem file' do
+    it 'does not register an offense' do
+      offenses = _investigate(cop, processed_source)
+
+      expect(offenses.size).to eq(0)
+    end
+  end
+
+  context 'with default configuration' do
+    let(:source) { 'print 1' }
+    let(:processed_source) { parse_source(source) }
+
+    before { allow(processed_source.buffer).to receive(:name).and_return(filename) }
+
+    context 'with gems.rb file path' do
+      let(:filename) { 'gems.rb' }
+
+      include_examples 'invalid gem file', 'gems.rb file was found but Gemfile is required.'
+    end
+
+    context 'with gems.locked file path' do
+      let(:filename) { 'gems.locked' }
+
+      include_examples 'invalid gem file',
+                       'Expected a Gemfile.lock with Gemfile but found gems.locked file.'
+    end
+
+    context 'with Gemfile file path' do
+      let(:filename) { 'Gemfile' }
+
+      include_examples 'valid gem file'
+    end
+
+    context 'with Gemfile.lock file path' do
+      let(:filename) { 'Gemfile.lock' }
+
+      include_examples 'valid gem file'
+    end
+  end
+
+  context 'with RequiresGemfile set to false' do
+    let(:source) { 'print 1' }
+    let(:processed_source) { parse_source(source) }
+    let(:cop_config) { { 'RequiresGemfile' => false } }
+
+    before { allow(processed_source.buffer).to receive(:name).and_return(filename) }
+
+    context 'with Gemfile file path' do
+      let(:filename) { 'Gemfile' }
+
+      include_examples 'invalid gem file', 'Gemfile was found but gems.rb file is required.'
+    end
+
+    context 'with Gemfile.lock file path' do
+      let(:filename) { 'Gemfile.lock' }
+
+      include_examples 'invalid gem file',
+                       'Expected a gems.locked file with gems.rb but found Gemfile.lock.'
+    end
+
+    context 'with gems.rb file path' do
+      let(:filename) { 'gems.rb' }
+
+      include_examples 'valid gem file'
+    end
+
+    context 'with gems.locked file path' do
+      let(:filename) { 'gems.locked' }
+
+      include_examples 'valid gem file'
+    end
+  end
+end