diff --git a/app/uploaders/attachment_uploader.rb b/app/uploaders/attachment_uploader.rb
index cd819dc9bff..0a166335b4e 100644
--- a/app/uploaders/attachment_uploader.rb
+++ b/app/uploaders/attachment_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AttachmentUploader < GitlabUploader
   include RecordsUploads::Concern
   include ObjectStorage::Concern
diff --git a/app/uploaders/avatar_uploader.rb b/app/uploaders/avatar_uploader.rb
index 5848e6c6994..b29ef57b071 100644
--- a/app/uploaders/avatar_uploader.rb
+++ b/app/uploaders/avatar_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AvatarUploader < GitlabUploader
   include UploaderHelper
   include RecordsUploads::Concern
diff --git a/app/uploaders/favicon_uploader.rb b/app/uploaders/favicon_uploader.rb
index 3639375d474..a0b275b56a9 100644
--- a/app/uploaders/favicon_uploader.rb
+++ b/app/uploaders/favicon_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class FaviconUploader < AttachmentUploader
   EXTENSION_WHITELIST = %w[png ico].freeze
 
diff --git a/app/uploaders/file_mover.rb b/app/uploaders/file_mover.rb
index bd7736ad74e..a7f8615e9ba 100644
--- a/app/uploaders/file_mover.rb
+++ b/app/uploaders/file_mover.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class FileMover
   attr_reader :secret, :file_name, :model, :update_field
 
diff --git a/app/uploaders/file_uploader.rb b/app/uploaders/file_uploader.rb
index 73606eb9f83..21292ddcf44 100644
--- a/app/uploaders/file_uploader.rb
+++ b/app/uploaders/file_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This class breaks the actual CarrierWave concept.
 # Every uploader should use a base_dir that is model agnostic so we can build
 # back URLs from base_dir-relative paths saved in the `Upload` model.
@@ -117,7 +119,7 @@ class FileUploader < GitlabUploader
   end
 
   def markdown_link
-    markdown = "[#{markdown_name}](#{secure_url})"
+    markdown = +"[#{markdown_name}](#{secure_url})"
     markdown.prepend("!") if image_or_video? || dangerous?
     markdown
   end
diff --git a/app/uploaders/gitlab_uploader.rb b/app/uploaders/gitlab_uploader.rb
index f8a237178d9..7919f126075 100644
--- a/app/uploaders/gitlab_uploader.rb
+++ b/app/uploaders/gitlab_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GitlabUploader < CarrierWave::Uploader::Base
   class_attribute :options
 
diff --git a/app/uploaders/job_artifact_uploader.rb b/app/uploaders/job_artifact_uploader.rb
index 2a5a830ce4f..855cf2fc21c 100644
--- a/app/uploaders/job_artifact_uploader.rb
+++ b/app/uploaders/job_artifact_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class JobArtifactUploader < GitlabUploader
   extend Workhorse::UploadPath
   include ObjectStorage::Concern
diff --git a/app/uploaders/legacy_artifact_uploader.rb b/app/uploaders/legacy_artifact_uploader.rb
index efb7893d153..b4d0d752016 100644
--- a/app/uploaders/legacy_artifact_uploader.rb
+++ b/app/uploaders/legacy_artifact_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LegacyArtifactUploader < GitlabUploader
   extend Workhorse::UploadPath
   include ObjectStorage::Concern
diff --git a/app/uploaders/lfs_object_uploader.rb b/app/uploaders/lfs_object_uploader.rb
index eb521a22ebc..f3d32e6b39d 100644
--- a/app/uploaders/lfs_object_uploader.rb
+++ b/app/uploaders/lfs_object_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LfsObjectUploader < GitlabUploader
   extend Workhorse::UploadPath
   include ObjectStorage::Concern
diff --git a/app/uploaders/namespace_file_uploader.rb b/app/uploaders/namespace_file_uploader.rb
index 1085ecb1700..52969762b7d 100644
--- a/app/uploaders/namespace_file_uploader.rb
+++ b/app/uploaders/namespace_file_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class NamespaceFileUploader < FileUploader
   # Re-Override
   def self.root
diff --git a/app/uploaders/object_storage.rb b/app/uploaders/object_storage.rb
index b8ecfc4ee2b..dad6e85fb56 100644
--- a/app/uploaders/object_storage.rb
+++ b/app/uploaders/object_storage.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'fog/aws'
 require 'carrierwave/storage/fog'
 
diff --git a/app/uploaders/personal_file_uploader.rb b/app/uploaders/personal_file_uploader.rb
index e3898b07730..25474b494ff 100644
--- a/app/uploaders/personal_file_uploader.rb
+++ b/app/uploaders/personal_file_uploader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PersonalFileUploader < FileUploader
   # Re-Override
   def self.root
diff --git a/app/uploaders/records_uploads.rb b/app/uploaders/records_uploads.rb
index 301f4681fcd..5795065ae11 100644
--- a/app/uploaders/records_uploads.rb
+++ b/app/uploaders/records_uploads.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module RecordsUploads
   module Concern
     extend ActiveSupport::Concern
diff --git a/app/uploaders/uploader_helper.rb b/app/uploaders/uploader_helper.rb
index 207928b61d0..2a2b54a9270 100644
--- a/app/uploaders/uploader_helper.rb
+++ b/app/uploaders/uploader_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Extra methods for uploader
 module UploaderHelper
   IMAGE_EXT = %w[png jpg jpeg gif bmp tiff ico].freeze
diff --git a/app/uploaders/workhorse.rb b/app/uploaders/workhorse.rb
index 782032cf516..84dc2791b9c 100644
--- a/app/uploaders/workhorse.rb
+++ b/app/uploaders/workhorse.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Workhorse
   module UploadPath
     def workhorse_upload_path
diff --git a/changelogs/unreleased/frozen-string-enable-app-uploaders.yml b/changelogs/unreleased/frozen-string-enable-app-uploaders.yml
new file mode 100644
index 00000000000..d43ca8bed8c
--- /dev/null
+++ b/changelogs/unreleased/frozen-string-enable-app-uploaders.yml
@@ -0,0 +1,5 @@
+---
+title: Enable frozen string in apps/validators/*.rb
+merge_request: 20382
+author: gfyoung
+type: other