diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index ef3dba6075..e023a63c50 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Remove deprecated fallback to `I18n.default_local` when `config.i18n.fallbacks` is empty.
+
+    *Rafael Mendonça França*
+
 *   Remove entries from local cache on `RedisCacheStore#delete_matched`
 
     Fixes #38627
diff --git a/activesupport/lib/active_support/i18n_railtie.rb b/activesupport/lib/active_support/i18n_railtie.rb
index 5c5dabfbd0..094f65ad6c 100644
--- a/activesupport/lib/active_support/i18n_railtie.rb
+++ b/activesupport/lib/active_support/i18n_railtie.rb
@@ -102,19 +102,6 @@ module I18n
           [I18n.default_locale]
         end
 
-      if args.empty? || args.first.is_a?(Hash)
-        ActiveSupport::Deprecation.warn(<<-MSG.squish)
-          Using I18n fallbacks with an empty `defaults` sets the defaults to
-          include the `default_locale`. This behavior will change in Rails 6.1.
-          If you desire the default locale to be included in the defaults, please
-          explicitly configure it with `config.i18n.fallbacks.defaults =
-          [I18n.default_locale]` or `config.i18n.fallbacks = [I18n.default_locale,
-          {...}]`. If you want to opt-in to the new behavior, use
-          `config.i18n.fallbacks.defaults = [nil, {...}]`.
-        MSG
-        args.unshift I18n.default_locale
-      end
-
       I18n.fallbacks = I18n::Locale::Fallbacks.new(*args)
     end
 
diff --git a/guides/source/6_1_release_notes.md b/guides/source/6_1_release_notes.md
index e3e1e09b39..5693f68251 100644
--- a/guides/source/6_1_release_notes.md
+++ b/guides/source/6_1_release_notes.md
@@ -284,6 +284,8 @@ Please refer to the [Changelog][active-support] for detailed changes.
 
 ### Removals
 
+*   Remove deprecated fallback to `I18n.default_local` when `config.i18n.fallbacks` is empty.
+
 ### Deprecations
 
 ### Notable changes
diff --git a/railties/test/application/initializers/i18n_test.rb b/railties/test/application/initializers/i18n_test.rb
index 8058052771..9936aadb46 100644
--- a/railties/test/application/initializers/i18n_test.rb
+++ b/railties/test/application/initializers/i18n_test.rb
@@ -237,7 +237,7 @@ fr:
     test "config.i18n.fallbacks.map = { :ca => :'es-ES' } initializes fallbacks with a mapping ca => es-ES" do
       I18n::Railtie.config.i18n.fallbacks.map = { ca: :'es-ES' }
       load_app
-      assert_fallbacks ca: [:ca, :"es-ES", :es, :en]
+      assert_fallbacks ca: [:ca, :"es-ES", :es]
     end
 
     test "[shortcut] config.i18n.fallbacks = [:'en-US'] initializes fallbacks with en-US as a fallback default" do
@@ -249,7 +249,7 @@ fr:
     test "[shortcut] config.i18n.fallbacks = [{ :ca => :'es-ES' }] initializes fallbacks with a mapping ca => es-ES" do
       I18n::Railtie.config.i18n.fallbacks = [{ ca: :'es-ES' }]
       load_app
-      assert_fallbacks ca: [:ca, :"es-ES", :es, :en]
+      assert_fallbacks ca: [:ca, :"es-ES", :es]
     end
 
     test "[shortcut] config.i18n.fallbacks = [:'en-US', { :ca => :'es-ES' }] initializes fallbacks with the given arguments" do