diff --git a/activemodel/lib/active_model/validator.rb b/activemodel/lib/active_model/validator.rb
index bddacc8c45..65cb1e5a88 100644
--- a/activemodel/lib/active_model/validator.rb
+++ b/activemodel/lib/active_model/validator.rb
@@ -106,7 +106,6 @@ module ActiveModel
     # Accepts options that will be made available through the +options+ reader.
     def initialize(options = {})
       @options  = options.except(:class).freeze
-      deprecated_setup(options)
     end
 
     # Returns the kind for this validator.
@@ -122,21 +121,6 @@ module ActiveModel
     def validate(record)
       raise NotImplementedError, "Subclasses must implement a validate(record) method."
     end
-
-    private
-    def deprecated_setup(options) # TODO: remove me in 4.2.
-      return unless respond_to?(:setup)
-      ActiveSupport::Deprecation.warn "The `Validator#setup` instance method is deprecated and will be removed on Rails 4.2. Do your setup in the constructor instead:
-
-class MyValidator < ActiveModel::Validator
-  def initialize(options={})
-    super
-    options[:class].send :attr_accessor, :custom_attribute
-  end
-end
-"
-      setup(options[:class])
-    end
   end
 
   # +EachValidator+ is a validator which iterates through the attributes given
diff --git a/activemodel/test/cases/validations_test.rb b/activemodel/test/cases/validations_test.rb
index 6a74ee353d..4fee704ef5 100644
--- a/activemodel/test/cases/validations_test.rb
+++ b/activemodel/test/cases/validations_test.rb
@@ -378,25 +378,4 @@ class ValidationsTest < ActiveModel::TestCase
     assert topic.invalid?
     assert duped.valid?
   end
-
-   # validator test:
-  def test_setup_is_deprecated_but_still_receives_klass # TODO: remove me in 4.2.
-    validator_class = Class.new(ActiveModel::Validator) do
-      def setup(klass)
-        @old_klass = klass
-      end
-
-      def validate(*)
-        @old_klass == Topic or raise "#setup didn't work"
-      end
-    end
-
-    assert_deprecated do
-      Topic.validates_with validator_class
-    end
-
-    t = Topic.new
-    t.valid?
-  end
-
 end