diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2364094ca00b..962bd6aab530 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 * [#5801](https://github.com/bbatsov/rubocop/pull/5801): Add new `Rails/RefuteMethods` cop. ([@koic][])
 * [#5805](https://github.com/bbatsov/rubocop/pull/5805): Add new `Rails/AssertNot` cop. ([@composerinteralia][])
 * [#4136](https://github.com/bbatsov/rubocop/issues/4136): Allow more robust `Layout/ClosingParenthesisIndentation` detection including method chaining. ([@jfelchner][])
+* [#5821](https://github.com/bbatsov/rubocop/pull/5821): Support `AR::Migration#up_only` for `Rails/ReversibleMigration` cop. ([@koic][])
 
 ### Bug fixes
 
diff --git a/lib/rubocop/cop/rails/reversible_migration.rb b/lib/rubocop/cop/rails/reversible_migration.rb
index 97b70c4e90e4..8e75eb4df3bf 100644
--- a/lib/rubocop/cop/rails/reversible_migration.rb
+++ b/lib/rubocop/cop/rails/reversible_migration.rb
@@ -157,7 +157,7 @@ class ReversibleMigration < Cop
 
         def on_send(node)
           return unless within_change_method?(node)
-          return if within_reversible_block?(node)
+          return if within_reversible_or_up_only_block?(node)
 
           check_irreversible_schema_statement_node(node)
           check_drop_table_node(node)
@@ -168,7 +168,7 @@ def on_send(node)
 
         def on_block(node)
           return unless within_change_method?(node)
-          return if within_reversible_block?(node)
+          return if within_reversible_or_up_only_block?(node)
 
           check_change_table_node(node.send_node, node.body)
         end
@@ -261,9 +261,11 @@ def within_change_method?(node)
           end
         end
 
-        def within_reversible_block?(node)
+        def within_reversible_or_up_only_block?(node)
           node.each_ancestor(:block).any? do |ancestor|
-            ancestor.block_type? && ancestor.send_node.method?(:reversible)
+            ancestor.block_type? &&
+              ancestor.send_node.method?(:reversible) ||
+              ancestor.send_node.method?(:up_only)
           end
         end
 
diff --git a/spec/rubocop/cop/rails/reversible_migration_spec.rb b/spec/rubocop/cop/rails/reversible_migration_spec.rb
index 4e732ddfafbd..c1d40994d20c 100644
--- a/spec/rubocop/cop/rails/reversible_migration_spec.rb
+++ b/spec/rubocop/cop/rails/reversible_migration_spec.rb
@@ -43,6 +43,10 @@ def change
     execute "ALTER TABLE `pages_linked_pages` ADD UNIQUE `page_id_linked_page_id` (`page_id`,`linked_page_id`)"
   RUBY
 
+  it_behaves_like :accepts, 'up_only', <<-RUBY
+    up_only { execute "UPDATE posts SET published = 'true'" }
+  RUBY
+
   context 'within block' do
     it_behaves_like :accepts, 'create_table', <<-RUBY
       [:users, :articles].each do |table|