diff --git a/CHANGELOG.md b/CHANGELOG.md
index 63b843d20..4e88b3368 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Support asserts with messages in `Rspec/BeEmpty`. ([@G-Rath])
 - Add support for `assert_empty`, `assert_not_empty` and `refute_empty` to `RSpec/Rails/MinitestAssertions`. ([@ydah])
 - Support correcting some `*_predicate` assertions in `RSpec/Rails/MinitestAssertions`. ([@G-Rath])
+- Support correcting `*_in_delta` assertions in `RSpec/Rails/MinitestAssertions`. ([@G-Rath])
 - Support correcting `*_match` assertions in `RSpec/Rails/MinitestAssertions`. ([@G-Rath])
 - Support correcting `*_instance_of` assertions in `RSpec/Rails/MinitestAssertions`. ([@G-Rath])
 - Support correcting `*_includes` assertions in `RSpec/Rails/MinitestAssertions`. ([@G-Rath])
diff --git a/lib/rubocop/cop/rspec/rails/minitest_assertions.rb b/lib/rubocop/cop/rspec/rails/minitest_assertions.rb
index 2b0dcf07d..e4d533b4a 100644
--- a/lib/rubocop/cop/rspec/rails/minitest_assertions.rb
+++ b/lib/rubocop/cop/rspec/rails/minitest_assertions.rb
@@ -127,6 +127,39 @@ def assertion
             end
           end
 
+          # :nodoc:
+          class InDeltaAssertion < BasicAssertion
+            MATCHERS = %i[
+              assert_in_delta
+              assert_not_in_delta
+              refute_in_delta
+            ].freeze
+
+            NODE_MATCHER_PATTERN = <<~PATTERN
+              (send nil? {:assert_in_delta :assert_not_in_delta :refute_in_delta} $_ $_ $!{sym str}? $_?)
+            PATTERN
+
+            def self.match(expected, actual, delta, failure_message)
+              return nil if delta.empty? && !failure_message.empty?
+
+              new(expected, actual, delta.first, failure_message.first)
+            end
+
+            def initialize(expected, actual, delta, fail_message)
+              super(expected, actual, fail_message)
+
+              @delta = delta&.source || '0.001'
+            end
+
+            def negated?(node)
+              !node.method?(:assert_in_delta)
+            end
+
+            def assertion
+              "be_within(#{@delta}).of(#{@expected})"
+            end
+          end
+
           # :nodoc:
           class PredicateAssertion < BasicAssertion
             MATCHERS = %i[
diff --git a/spec/rubocop/cop/rspec/rails/minitest_assertions_spec.rb b/spec/rubocop/cop/rspec/rails/minitest_assertions_spec.rb
index 0fdbe8af5..ac427b063 100644
--- a/spec/rubocop/cop/rspec/rails/minitest_assertions_spec.rb
+++ b/spec/rubocop/cop/rspec/rails/minitest_assertions_spec.rb
@@ -271,6 +271,127 @@
     end
   end
 
+  context 'with in_delta assertions' do
+    it 'registers an offense when using `assert_in_delta`' do
+      expect_offense(<<~RUBY)
+        assert_in_delta(a, b)
+        ^^^^^^^^^^^^^^^^^^^^^ Use `expect(b).to be_within(0.001).of(a)`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        expect(b).to be_within(0.001).of(a)
+      RUBY
+    end
+
+    it 'registers an offense when using `assert_in_delta` with ' \
+       'no parentheses' do
+      expect_offense(<<~RUBY)
+        assert_in_delta a, b
+        ^^^^^^^^^^^^^^^^^^^^ Use `expect(b).to be_within(0.001).of(a)`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        expect(b).to be_within(0.001).of(a)
+      RUBY
+    end
+
+    it 'registers an offense when using `assert_in_delta` with ' \
+       'a custom delta' do
+      expect_offense(<<~RUBY)
+        assert_in_delta a, b, 1
+        ^^^^^^^^^^^^^^^^^^^^^^^ Use `expect(b).to be_within(1).of(a)`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        expect(b).to be_within(1).of(a)
+      RUBY
+    end
+
+    it 'registers an offense when using `assert_in_delta` with ' \
+       'a custom delta from a variable' do
+      expect_offense(<<~RUBY)
+        delta = 1
+
+        assert_in_delta a, b, delta
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `expect(b).to be_within(delta).of(a)`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        delta = 1
+
+        expect(b).to be_within(delta).of(a)
+      RUBY
+    end
+
+    it 'registers an offense when using `assert_in_delta` with ' \
+       'a custom delta and a failure message' do
+      expect_offense(<<~RUBY)
+        assert_in_delta a, b, 1, "must be within delta"
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `expect(b).to(be_within(1).of(a), "must be within delta")`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        expect(b).to(be_within(1).of(a), "must be within delta")
+      RUBY
+    end
+
+    it 'registers an offense when using `assert_in_delta` with ' \
+       'multi-line arguments' do
+      expect_offense(<<~RUBY)
+        assert_in_delta(a,
+        ^^^^^^^^^^^^^^^^^^ Use `expect(b).to be_within(1).of(a)`.
+                      b,
+                      1)
+      RUBY
+
+      expect_correction(<<~RUBY)
+        expect(b).to be_within(1).of(a)
+      RUBY
+    end
+
+    it 'registers an offense when using `assert_not_in_delta`' do
+      expect_offense(<<~RUBY)
+        assert_not_in_delta a, b
+        ^^^^^^^^^^^^^^^^^^^^^^^^ Use `expect(b).not_to be_within(0.001).of(a)`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        expect(b).not_to be_within(0.001).of(a)
+      RUBY
+    end
+
+    it 'registers an offense when using `refute_in_delta`' do
+      expect_offense(<<~RUBY)
+        refute_in_delta a, b
+        ^^^^^^^^^^^^^^^^^^^^ Use `expect(b).not_to be_within(0.001).of(a)`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        expect(b).not_to be_within(0.001).of(a)
+      RUBY
+    end
+
+    it 'does not register an offense when ' \
+       'using `expect(b).to be_within(1).of(a)`' do
+      expect_no_offenses(<<~RUBY)
+        expect(b).to be_within(1).of(a)
+      RUBY
+    end
+
+    it 'does not register an offense when ' \
+       'using `expect(b).not_to be_within(1).of(a)`' do
+      expect_no_offenses(<<~RUBY)
+        expect(b).not_to be_within(1).of(a)
+      RUBY
+    end
+
+    it 'does not register an offense when the delta is missing' do
+      expect_no_offenses(<<~RUBY)
+        assert_in_delta a, b, "whoops, we forgot about the actual delta!"
+      RUBY
+    end
+  end
+
   context 'with match assertions' do
     it 'registers an offense when using `assert_match`' do
       expect_offense(<<~RUBY)