diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1f02093ef5..2a6756710e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@
 
 ## master (unreleased)
 
+* [#1035](https://github.com/rubocop/rubocop-rails/pull/1035): Add cop Rails/AcceptsNestedAttributesForUpdateOnly. ([@olivier-thatch][])
+
 ## 2.20.2 (2023-06-20)
 
 ### Bug fixes
@@ -894,3 +896,4 @@
 [@masato-bkn]: https://github.com/masato-bkn
 [@splattael]: https://github.com/splattael
 [@samrjenkins]: https://github.com/samrjenkins
+[@olivier-thatch]: https://github.com/olivier-thatch
diff --git a/config/default.yml b/config/default.yml
index 0fef0c30d5..a489d15867 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -65,6 +65,14 @@ Rails:
   Enabled: true
   DocumentationBaseURL: https://docs.rubocop.org/rubocop-rails
 
+Rails/AcceptsNestedAttributesForUpdateOnly:
+  Description: 'Define the update_only option to the accepts_nested_attributes_for attributes writers.'
+  StyleGuide: 'https://rails.rubystyle.guide#accepts_nested_attributes_for-update_only-option'
+  Enabled: false
+  VersionAdded: '2.21'
+  Include:
+    - app/models/**/*.rb
+
 Rails/ActionControllerFlashBeforeRender:
   Description: 'Use `flash.now` instead of `flash` before `render`.'
   Enabled: 'pending'
diff --git a/docs/modules/ROOT/pages/cops.adoc b/docs/modules/ROOT/pages/cops.adoc
index c56351643e..10bac2464b 100644
--- a/docs/modules/ROOT/pages/cops.adoc
+++ b/docs/modules/ROOT/pages/cops.adoc
@@ -16,6 +16,7 @@ based on the https://rails.rubystyle.guide/[Rails Style Guide].
 
 === Department xref:cops_rails.adoc[Rails]
 
+* xref:cops_rails.adoc#railsacceptsnestedattributesforupdateonly[Rails/AcceptsNestedAttributesForUpdateOnly]
 * xref:cops_rails.adoc#railsactioncontrollerflashbeforerender[Rails/ActionControllerFlashBeforeRender]
 * xref:cops_rails.adoc#railsactioncontrollertestcase[Rails/ActionControllerTestCase]
 * xref:cops_rails.adoc#railsactionfilter[Rails/ActionFilter]
diff --git a/docs/modules/ROOT/pages/cops_rails.adoc b/docs/modules/ROOT/pages/cops_rails.adoc
index 3041223985..60b0f3d721 100644
--- a/docs/modules/ROOT/pages/cops_rails.adoc
+++ b/docs/modules/ROOT/pages/cops_rails.adoc
@@ -1,5 +1,51 @@
 = Rails
 
+== Rails/AcceptsNestedAttributesForUpdateOnly
+
+|===
+| Enabled by default | Safe | Supports autocorrection | Version Added | Version Changed
+
+| Disabled
+| Yes
+| No
+| 2.21
+| -
+|===
+
+Looks for `accepts_nested_attributes_for` attributes writers that don't
+specify an `:update_only` option.
+
+=== Examples
+
+[source,ruby]
+----
+# bad
+class Member < ActiveRecord::Base
+  has_one :avatar
+  accepts_nested_attributes_for :avatar
+end
+
+# good
+class Member < ActiveRecord::Base
+  has_one :avatar
+  accepts_nested_attributes_for :avatar, update_only: true
+end
+----
+
+=== Configurable attributes
+
+|===
+| Name | Default value | Configurable values
+
+| Include
+| `+app/models/**/*.rb+`
+| Array
+|===
+
+=== References
+
+* https://rails.rubystyle.guide#accepts_nested_attributes_for-update_only-option
+
 == Rails/ActionControllerFlashBeforeRender
 
 |===
diff --git a/lib/rubocop/cop/rails/accepts_nested_attributes_for_update_only.rb b/lib/rubocop/cop/rails/accepts_nested_attributes_for_update_only.rb
new file mode 100644
index 0000000000..2b1b791ed5
--- /dev/null
+++ b/lib/rubocop/cop/rails/accepts_nested_attributes_for_update_only.rb
@@ -0,0 +1,115 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # Looks for `accepts_nested_attributes_for` attributes writers that don't
+      # specify an `:update_only` option.
+      #
+      # @example
+      #   # bad
+      #   class Member < ActiveRecord::Base
+      #     has_one :avatar
+      #     accepts_nested_attributes_for :avatar
+      #   end
+      #
+      #   # good
+      #   class Member < ActiveRecord::Base
+      #     has_one :avatar
+      #     accepts_nested_attributes_for :avatar, update_only: true
+      #   end
+      class AcceptsNestedAttributesForUpdateOnly < Base
+        MSG = 'Specify a `:update_only` option.'
+        RESTRICT_ON_SEND = %i[accepts_nested_attributes_for].freeze
+
+        def_node_search :active_resource_class?, <<~PATTERN
+          (const (const {nil? cbase} :ActiveResource) :Base)
+        PATTERN
+
+        def_node_matcher :accepts_nested_attributes_for_without_options?, <<~PATTERN
+          (send _ {:accepts_nested_attributes_for} _)
+        PATTERN
+
+        def_node_matcher :accepts_nested_attributes_for_with_options?, <<~PATTERN
+          (send _ {:accepts_nested_attributes_for} ... (hash $...))
+        PATTERN
+
+        def_node_matcher :update_only_option?, <<~PATTERN
+          (pair (sym :update_only) {!nil (nil)})
+        PATTERN
+
+        def_node_matcher :with_options_block, <<~PATTERN
+          (block
+            (send nil? :with_options
+              (hash $...))
+            (args) ...)
+        PATTERN
+
+        def_node_matcher :accepts_nested_attributes_for_extension_block?, <<~PATTERN
+          (block
+            (send nil? :accepts_nested_attributes_for _)
+            (args) ...)
+        PATTERN
+
+        def on_send(node)
+          return if active_resource?(node.parent)
+          return if !accepts_nested_attributes_for_without_options?(node) && \
+                    valid_options?(accepts_nested_attributes_for_with_options?(node))
+          return if valid_options_in_with_options_block?(node)
+
+          add_offense(node.loc.selector)
+        end
+
+        private
+
+        def valid_options_in_with_options_block?(node)
+          return true unless node.parent
+
+          n = node.parent.begin_type?
+          n ||= accepts_nested_attributes_for_extension_block?(node.parent) ? node.parent.parent : node.parent
+
+          contain_valid_options_in_with_options_block?(n)
+        end
+
+        def contain_valid_options_in_with_options_block?(node)
+          if (options = with_options_block(node))
+            return true if valid_options?(options)
+
+            return false unless node.parent
+
+            return true if contain_valid_options_in_with_options_block?(node.parent.parent)
+          end
+
+          false
+        end
+
+        def valid_options?(options)
+          return false if options.nil?
+
+          options = extract_option_if_kwsplat(options)
+
+          return true unless options
+          return true if options.any? do |o|
+            update_only_option?(o)
+          end
+
+          false
+        end
+
+        def extract_option_if_kwsplat(options)
+          if options.first.kwsplat_type? && options.first.children.first.hash_type?
+            return options.first.children.first.pairs
+          end
+
+          options
+        end
+
+        def active_resource?(node)
+          return false if node.nil?
+
+          active_resource_class?(node)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/rubocop/cop/rails_cops.rb b/lib/rubocop/cop/rails_cops.rb
index 5e0db983d6..8e7340415f 100644
--- a/lib/rubocop/cop/rails_cops.rb
+++ b/lib/rubocop/cop/rails_cops.rb
@@ -8,6 +8,7 @@
 require_relative 'mixin/migrations_helper'
 require_relative 'mixin/target_rails_version'
 
+require_relative 'rails/accepts_nested_attributes_for_update_only'
 require_relative 'rails/action_controller_flash_before_render'
 require_relative 'rails/action_controller_test_case'
 require_relative 'rails/action_filter'
diff --git a/spec/rubocop/cop/rails/accepts_nested_attributes_for_update_only_spec.rb b/spec/rubocop/cop/rails/accepts_nested_attributes_for_update_only_spec.rb
new file mode 100644
index 0000000000..b520a00189
--- /dev/null
+++ b/spec/rubocop/cop/rails/accepts_nested_attributes_for_update_only_spec.rb
@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rails::AcceptsNestedAttributesForUpdateOnly, :config do
+  context 'accepts_nested_attributes_for' do
+    it 'registers an offense when not specifying any options' do
+      expect_offense(<<~RUBY)
+        class Member < ApplicationRecord
+          has_one :avatar
+          accepts_nested_attributes_for :avatar
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Specify a `:update_only` option.
+        end
+      RUBY
+    end
+
+    it 'registers an offense when missing an explicit `:update_only` flag' do
+      expect_offense(<<~RUBY)
+        class Member < ApplicationRecord
+          has_one :avatar
+          accepts_nested_attributes_for :avatar, reject_if: :all_blank
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Specify a `:update_only` option.
+        end
+      RUBY
+    end
+
+    it 'does not register an offense when specifying `:update_only` flag' do
+      expect_no_offenses(<<~RUBY)
+        class Member < ApplicationRecord
+          has_one :avatar
+          accepts_nested_attributes_for :avatar, update_only: true
+        end
+      RUBY
+    end
+
+    it 'does not register an offense when specifying `:update_only` flag with double splat' do
+      expect_no_offenses(<<~RUBY)
+        class Member < ApplicationRecord
+          has_one :avatar
+          accepts_nested_attributes_for :avatar, **{update_only: true}
+        end
+      RUBY
+    end
+
+    it 'registers an offense when a variable passed with double splat' do
+      expect_offense(<<~RUBY)
+        class Member < ApplicationRecord
+          has_one :avatar
+          accepts_nested_attributes_for :avatar, **bar
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Specify a `:update_only` option.
+        end
+      RUBY
+    end
+
+    context 'with_options update_only: true' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          class Member < ApplicationRecord
+            has_one :avatar
+            with_options update_only: true do
+              accepts_nested_attributes_for :avatar
+            end
+          end
+        RUBY
+      end
+
+      it 'does not register an offense for using `reject_if` option' do
+        expect_no_offenses(<<~RUBY)
+          class Member < ApplicationRecord
+            has_one :avatar
+            with_options update_only: true do
+              accepts_nested_attributes_for :avatar, reject_if: :all_blank
+            end
+          end
+        RUBY
+      end
+    end
+  end
+
+  context 'when an Active Record model does not have any associations' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<~RUBY)
+        class Member < ApplicationRecord
+        end
+      RUBY
+    end
+  end
+end