diff --git a/CHANGELOG.md b/CHANGELOG.md
index 86ff6b72686..8ce8c9ad717 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@
 * [#8825](https://github.com/rubocop-hq/rubocop/issues/8825): Fix crash in `Style/ExplicitBlockArgument` when code is called outside of a method. ([@ghiculescu][])
 * [#8718](https://github.com/rubocop-hq/rubocop/issues/8718): Fix undefined methods of pseudo location. ([@ybiquitous][])
 * [#8354](https://github.com/rubocop-hq/rubocop/issues/8354): Detect regexp named captures in `Style/CaseLikeIf` cop. ([@dsavochkin][])
+* [#8821](https://github.com/rubocop-hq/rubocop/issues/8821): Fix an incorrect autocorrect for `Style/NestedTernaryOperator` when using a nested ternary operator expression with no parentheses on the outside. ([@koic][])
 * [#8834](https://github.com/rubocop-hq/rubocop/issues/8834): Fix a false positive for `Style/ParenthesesAsGroupedExpression` when method argument parentheses are omitted and hash argument key is enclosed in parentheses. ([@koic][])
 * [#8830](https://github.com/rubocop-hq/rubocop/issues/8830): Fix bad autocorrect of `Style/StringConcatenation` when string includes double quotes. ([@tleish][])
 * [#8807](https://github.com/rubocop-hq/rubocop/pull/8807): Fix a false positive for `Style/RedundantCondition` when using assignment by hash key access. ([@koic][])
diff --git a/lib/rubocop/cop/style/nested_ternary_operator.rb b/lib/rubocop/cop/style/nested_ternary_operator.rb
index 482c3273e78..6ebcb462f00 100644
--- a/lib/rubocop/cop/style/nested_ternary_operator.rb
+++ b/lib/rubocop/cop/style/nested_ternary_operator.rb
@@ -49,6 +49,8 @@ def if_node(node)
         end
 
         def remove_parentheses(source)
+          return source unless source.start_with?('(')
+
           source.gsub(/\A\(/, '').gsub(/\)\z/, '')
         end
       end
diff --git a/spec/rubocop/cop/style/nested_ternary_operator_spec.rb b/spec/rubocop/cop/style/nested_ternary_operator_spec.rb
index 373ab9c6da1..5013f0cd544 100644
--- a/spec/rubocop/cop/style/nested_ternary_operator_spec.rb
+++ b/spec/rubocop/cop/style/nested_ternary_operator_spec.rb
@@ -34,6 +34,21 @@
     RUBY
   end
 
+  it 'registers an offense and corrects for a nested ternary operator expression with no parentheses on the outside' do
+    expect_offense(<<~RUBY)
+      x ? y + (z ? 1 : 0) : nil
+               ^^^^^^^^^ Ternary operators must not be nested. Prefer `if` or `else` constructs instead.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      if x
+        y + (z ? 1 : 0)
+      else
+        nil
+      end
+    RUBY
+  end
+
   it 'accepts a non-nested ternary operator within an if' do
     expect_no_offenses(<<~RUBY)
       a = if x