diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8b73d5963bc..5b8b41c3dc0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5722,3 +5722,4 @@
 [@timlkelly]: https://github.com/timlkelly
 [@AirWick219]: https://github.com/AirWick219
 [@markburns]: https://github.com/markburns
+[@gregfletch]: https://github.com/gregfletch
diff --git a/changelog/fix_make_comment_annotation_style_configurable.md b/changelog/fix_make_comment_annotation_style_configurable.md
new file mode 100644
index 00000000000..64b4924488a
--- /dev/null
+++ b/changelog/fix_make_comment_annotation_style_configurable.md
@@ -0,0 +1 @@
+* [#9890](https://github.com/rubocop/rubocop/issues/9890): Make colon after comment annotation configurable. ([@gregfletch][])
diff --git a/config/default.yml b/config/default.yml
index 3cf7c7ea2ae..11af268c520 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -3150,6 +3150,7 @@ Style/CommentAnnotation:
     - HACK
     - REVIEW
     - NOTE
+  RequireColon: true
 
 Style/CommentedKeyword:
   Description: 'Do not place comments on the same line as certain keywords.'
diff --git a/lib/rubocop/cop/style/comment_annotation.rb b/lib/rubocop/cop/style/comment_annotation.rb
index fb62a145aa5..24f7b092a0a 100644
--- a/lib/rubocop/cop/style/comment_annotation.rb
+++ b/lib/rubocop/cop/style/comment_annotation.rb
@@ -12,7 +12,7 @@ module Style
       # incorrect registering of keywords (eg. `review`) inside a paragraph as an
       # annotation.
       #
-      # @example
+      # @example RequireColon: true (default)
       #   # bad
       #   # TODO make better
       #
@@ -36,14 +36,36 @@ module Style
       #
       #   # good
       #   # OPTIMIZE: does not work
+      #
+      # @example RequireColon: false
+      #   # bad
+      #   # TODO: make better
+      #
+      #   # good
+      #   # TODO make better
+      #
+      #   # bad
+      #   # fixme does not work
+      #
+      #   # good
+      #   # FIXME does not work
+      #
+      #   # bad
+      #   # Optimize does not work
+      #
+      #   # good
+      #   # OPTIMIZE does not work
       class CommentAnnotation < Base
         include AnnotationComment
         include RangeHelp
         extend AutoCorrector
 
-        MSG = 'Annotation keywords like `%<keyword>s` should be all ' \
-              'upper case, followed by a colon, and a space, ' \
-              'then a note describing the problem.'
+        MSG_COLON_STYLE = 'Annotation keywords like `%<keyword>s` should be all ' \
+                          'upper case, followed by a colon, and a space, ' \
+                          'then a note describing the problem.'
+        MSG_SPACE_STYLE = 'Annotation keywords like `%<keyword>s` should be all ' \
+                          'upper case, followed by a space, ' \
+                          'then a note describing the problem.'
         MISSING_NOTE = 'Annotation comment, with keyword `%<keyword>s`, is missing a note.'
 
         def on_new_investigation
@@ -63,13 +85,15 @@ def on_new_investigation
         private
 
         def register_offense(range, note, first_word)
+          message = requires_colon? ? MSG_COLON_STYLE : MSG_SPACE_STYLE
+
           add_offense(
             range,
-            message: format(note ? MSG : MISSING_NOTE, keyword: first_word)
+            message: format(note ? message : MISSING_NOTE, keyword: first_word)
           ) do |corrector|
             next if note.nil?
 
-            corrector.replace(range, "#{first_word.upcase}: ")
+            correct_offense(corrector, range, first_word)
           end
         end
 
@@ -92,8 +116,28 @@ def concat_length(*args)
         end
 
         def correct_annotation?(first_word, colon, space, note)
+          return correct_colon_annotation?(first_word, colon, space, note) if requires_colon?
+
+          correct_space_annotation?(first_word, colon, space, note)
+        end
+
+        def correct_colon_annotation?(first_word, colon, space, note)
           keyword?(first_word) && (colon && space && note || !colon && !note)
         end
+
+        def correct_space_annotation?(first_word, colon, space, note)
+          keyword?(first_word) && (!colon && space && note || !colon && !note)
+        end
+
+        def correct_offense(corrector, range, first_word)
+          return corrector.replace(range, "#{first_word.upcase}: ") if requires_colon?
+
+          corrector.replace(range, "#{first_word.upcase} ")
+        end
+
+        def requires_colon?
+          cop_config['RequireColon']
+        end
       end
     end
   end
diff --git a/spec/rubocop/cop/style/comment_annotation_spec.rb b/spec/rubocop/cop/style/comment_annotation_spec.rb
index 43ae1794e84..6dd3b57a464 100644
--- a/spec/rubocop/cop/style/comment_annotation_spec.rb
+++ b/spec/rubocop/cop/style/comment_annotation_spec.rb
@@ -1,144 +1,273 @@
 # frozen_string_literal: true
 
 RSpec.describe RuboCop::Cop::Style::CommentAnnotation, :config do
-  let(:cop_config) { { 'Keywords' => %w[TODO FIXME OPTIMIZE HACK REVIEW] } }
+  context 'with default RequireColon configuration (colon + space)' do
+    let(:cop_config) { { 'Keywords' => %w[TODO FIXME OPTIMIZE HACK REVIEW] } }
 
-  context 'missing colon' do
-    it 'registers an offense and adds colon' do
-      expect_offense(<<~RUBY)
-        # TODO make better
-          ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
-      RUBY
+    context 'missing colon' do
+      it 'registers an offense and adds colon' do
+        expect_offense(<<~RUBY)
+          # TODO make better
+            ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
+        RUBY
 
-      expect_correction(<<~RUBY)
-        # TODO: make better
-      RUBY
+        expect_correction(<<~RUBY)
+          # TODO: make better
+        RUBY
+      end
     end
-  end
 
-  context 'with configured keyword' do
-    let(:cop_config) { { 'Keywords' => %w[ISSUE] } }
+    context 'with configured keyword' do
+      let(:cop_config) { { 'Keywords' => %w[ISSUE] } }
 
-    it 'registers an offense for a missing colon after the word' do
-      expect_offense(<<~RUBY)
-        # ISSUE wrong order
-          ^^^^^^ Annotation keywords like `ISSUE` should be all upper case, followed by a colon, and a space, then a note describing the problem.
-      RUBY
+      it 'registers an offense for a missing colon after the word' do
+        expect_offense(<<~RUBY)
+          # ISSUE wrong order
+            ^^^^^^ Annotation keywords like `ISSUE` should be all upper case, followed by a colon, and a space, then a note describing the problem.
+        RUBY
 
-      expect_correction(<<~RUBY)
-        # ISSUE: wrong order
-      RUBY
+        expect_correction(<<~RUBY)
+          # ISSUE: wrong order
+        RUBY
+      end
     end
-  end
 
-  context 'missing space after colon' do
-    it 'registers an offense and adds space' do
-      expect_offense(<<~RUBY)
-        # TODO:make better
-          ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
-      RUBY
+    context 'missing space after colon' do
+      it 'registers an offense and adds space' do
+        expect_offense(<<~RUBY)
+          # TODO:make better
+            ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
+        RUBY
 
-      expect_correction(<<~RUBY)
-        # TODO: make better
-      RUBY
+        expect_correction(<<~RUBY)
+          # TODO: make better
+        RUBY
+      end
     end
-  end
 
-  context 'lower case keyword' do
-    it 'registers an offense and upcases' do
-      expect_offense(<<~RUBY)
-        # fixme: does not work
-          ^^^^^^^ Annotation keywords like `fixme` should be all upper case, followed by a colon, and a space, then a note describing the problem.
-      RUBY
+    context 'lower case keyword' do
+      it 'registers an offense and upcases' do
+        expect_offense(<<~RUBY)
+          # fixme: does not work
+            ^^^^^^^ Annotation keywords like `fixme` should be all upper case, followed by a colon, and a space, then a note describing the problem.
+        RUBY
 
-      expect_correction(<<~RUBY)
-        # FIXME: does not work
-      RUBY
+        expect_correction(<<~RUBY)
+          # FIXME: does not work
+        RUBY
+      end
     end
-  end
 
-  context 'capitalized keyword' do
-    it 'registers an offense and upcases' do
-      expect_offense(<<~RUBY)
-        # Optimize: does not work
-          ^^^^^^^^^^ Annotation keywords like `Optimize` should be all upper case, followed by a colon, and a space, then a note describing the problem.
-      RUBY
+    context 'capitalized keyword' do
+      it 'registers an offense and upcases' do
+        expect_offense(<<~RUBY)
+          # Optimize: does not work
+            ^^^^^^^^^^ Annotation keywords like `Optimize` should be all upper case, followed by a colon, and a space, then a note describing the problem.
+        RUBY
+
+        expect_correction(<<~RUBY)
+          # OPTIMIZE: does not work
+        RUBY
+      end
+    end
 
-      expect_correction(<<~RUBY)
-        # OPTIMIZE: does not work
+    context 'upper case keyword with colon by no note' do
+      it 'registers an offense without auto-correction' do
+        expect_offense(<<~RUBY)
+          # HACK:
+            ^^^^^ Annotation comment, with keyword `HACK`, is missing a note.
+        RUBY
+
+        expect_no_corrections
+      end
+    end
+
+    it 'accepts upper case keyword with colon, space and note' do
+      expect_no_offenses('# REVIEW: not sure about this')
+    end
+
+    it 'accepts upper case keyword alone' do
+      expect_no_offenses('# OPTIMIZE')
+    end
+
+    it 'accepts a comment that is obviously a code example' do
+      expect_no_offenses('# Todo.destroy(1)')
+    end
+
+    it 'accepts a keyword that is just the beginning of a sentence' do
+      expect_no_offenses(<<~RUBY)
+        # Optimize if you want. I wouldn't recommend it.
+        # Hack is a fun game.
       RUBY
     end
-  end
 
-  context 'upper case keyword with colon by no note' do
-    it 'registers an offense without auto-correction' do
-      expect_offense(<<~RUBY)
-        # HACK:
-          ^^^^^ Annotation comment, with keyword `HACK`, is missing a note.
+    it 'accepts a keyword that is somewhere in a sentence' do
+      expect_no_offenses(<<~RUBY)
+        # Example: There are three reviews, with ranks 1, 2, and 3. A new
+        # review is saved with rank 2. The two reviews that originally had
+        # ranks 2 and 3 will have their ranks increased to 3 and 4.
       RUBY
+    end
 
-      expect_no_corrections
+    context 'when a keyword is not in the configuration' do
+      let(:cop_config) { { 'Keywords' => %w[FIXME OPTIMIZE HACK REVIEW] } }
+
+      it 'accepts the word without colon' do
+        expect_no_offenses('# TODO make better')
+      end
     end
-  end
 
-  it 'accepts upper case keyword with colon, space and note' do
-    expect_no_offenses('# REVIEW: not sure about this')
-  end
+    context 'offenses in consecutive inline comments' do
+      it 'registers each of them' do
+        expect_offense(<<~RUBY)
+          class ToBeDone
+            ITEMS = [
+              '', # TODO Item 1
+                    ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
+              '', # TODO Item 2
+                    ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
+            ].freeze
+          end
+        RUBY
+      end
+    end
 
-  it 'accepts upper case keyword alone' do
-    expect_no_offenses('# OPTIMIZE')
+    context 'multiline comment' do
+      it 'only registers an offense on the first line' do
+        expect_offense(<<~RUBY)
+          # TODO line 1
+            ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
+          # TODO line 2
+          # TODO line 3
+        RUBY
+      end
+    end
   end
 
-  it 'accepts a comment that is obviously a code example' do
-    expect_no_offenses('# Todo.destroy(1)')
-  end
+  context 'with RequireColon configuration set to false' do
+    let(:cop_config) do
+      {
+        'Keywords' => %w[TODO FIXME OPTIMIZE HACK REVIEW],
+        'RequireColon' => false
+      }
+    end
 
-  it 'accepts a keyword that is just the beginning of a sentence' do
-    expect_no_offenses(<<~RUBY)
-      # Optimize if you want. I wouldn't recommend it.
-      # Hack is a fun game.
-    RUBY
-  end
+    context 'with colon' do
+      it 'registers an offense and removes colon' do
+        expect_offense(<<~RUBY)
+          # TODO: make better
+            ^^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a space, then a note describing the problem.
+        RUBY
 
-  it 'accepts a keyword that is somewhere in a sentence' do
-    expect_no_offenses(<<~RUBY)
-      # Example: There are three reviews, with ranks 1, 2, and 3. A new
-      # review is saved with rank 2. The two reviews that originally had
-      # ranks 2 and 3 will have their ranks increased to 3 and 4.
-    RUBY
-  end
+        expect_correction(<<~RUBY)
+          # TODO make better
+        RUBY
+      end
+    end
+
+    context 'with configured keyword' do
+      let(:cop_config) { { 'Keywords' => %w[ISSUE], 'RequireColon' => false } }
 
-  context 'when a keyword is not in the configuration' do
-    let(:cop_config) { { 'Keywords' => %w[FIXME OPTIMIZE HACK REVIEW] } }
+      it 'registers an offense for containing a colon after the word' do
+        expect_offense(<<~RUBY)
+          # ISSUE: wrong order
+            ^^^^^^^ Annotation keywords like `ISSUE` should be all upper case, followed by a space, then a note describing the problem.
+        RUBY
 
-    it 'accepts the word without colon' do
-      expect_no_offenses('# TODO make better')
+        expect_correction(<<~RUBY)
+          # ISSUE wrong order
+        RUBY
+      end
+    end
+
+    context 'lower case keyword' do
+      it 'registers an offense and upcases' do
+        expect_offense(<<~RUBY)
+          # fixme does not work
+            ^^^^^^ Annotation keywords like `fixme` should be all upper case, followed by a space, then a note describing the problem.
+        RUBY
+
+        expect_correction(<<~RUBY)
+          # FIXME does not work
+        RUBY
+      end
+    end
+
+    context 'upper case keyword with colon by no note' do
+      it 'registers an offense without auto-correction' do
+        expect_offense(<<~RUBY)
+          # HACK:
+            ^^^^^ Annotation comment, with keyword `HACK`, is missing a note.
+        RUBY
+
+        expect_no_corrections
+      end
     end
-  end
 
-  context 'offenses in consecutive inline comments' do
-    it 'registers each of them' do
-      expect_offense(<<~RUBY)
-        class ToBeDone
-          ITEMS = [
-            '', # TODO Item 1
-                  ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
-            '', # TODO Item 2
-                  ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
-          ].freeze
-        end
+    it 'accepts upper case keyword with colon, space and note' do
+      expect_no_offenses('# REVIEW not sure about this')
+    end
+
+    it 'accepts upper case keyword alone' do
+      expect_no_offenses('# OPTIMIZE')
+    end
+
+    it 'accepts a comment that is obviously a code example' do
+      expect_no_offenses('# Todo.destroy(1)')
+    end
+
+    it 'accepts a keyword that is just the beginning of a sentence' do
+      expect_no_offenses(<<~RUBY)
+        # Optimize if you want. I wouldn't recommend it.
+        # Hack is a fun game.
       RUBY
     end
-  end
 
-  context 'multiline comment' do
-    it 'only registers an offense on the first line' do
-      expect_offense(<<~RUBY)
-        # TODO line 1
-          ^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a colon, and a space, then a note describing the problem.
-        # TODO line 2
-        # TODO line 3
+    it 'accepts a keyword that is somewhere in a sentence' do
+      expect_no_offenses(<<~RUBY)
+        # Example: There are three reviews, with ranks 1, 2, and 3. A new
+        # review is saved with rank 2. The two reviews that originally had
+        # ranks 2 and 3 will have their ranks increased to 3 and 4.
       RUBY
     end
+
+    context 'when a keyword is not in the configuration' do
+      let(:cop_config) do
+        {
+          'Keywords' => %w[FIXME OPTIMIZE HACK REVIEW],
+          'RequireColon' => false
+        }
+      end
+
+      it 'accepts the word with colon' do
+        expect_no_offenses('# TODO: make better')
+      end
+    end
+
+    context 'offenses in consecutive inline comments' do
+      it 'registers each of them' do
+        expect_offense(<<~RUBY)
+          class ToBeDone
+            ITEMS = [
+              '', # TODO: Item 1
+                    ^^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a space, then a note describing the problem.
+              '', # TODO: Item 2
+                    ^^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a space, then a note describing the problem.
+            ].freeze
+          end
+        RUBY
+      end
+    end
+
+    context 'multiline comment' do
+      it 'only registers an offense on the first line' do
+        expect_offense(<<~RUBY)
+          # TODO: line 1
+            ^^^^^^ Annotation keywords like `TODO` should be all upper case, followed by a space, then a note describing the problem.
+          # TODO: line 2
+          # TODO: line 3
+        RUBY
+      end
+    end
   end
 end