diff --git a/changelog/fix_a_false_positive_for_naming_constant_name.md b/changelog/fix_a_false_positive_for_naming_constant_name.md
new file mode 100644
index 00000000000..c3e2034f43a
--- /dev/null
+++ b/changelog/fix_a_false_positive_for_naming_constant_name.md
@@ -0,0 +1 @@
+* [#11865](https://github.com/rubocop/rubocop/pull/11865): Fix an error for `Naming/ConstantName` when assigning a constant from an empty branch of `else`. ([@koic][])
diff --git a/lib/rubocop/cop/naming/constant_name.rb b/lib/rubocop/cop/naming/constant_name.rb
index 2c045aaee6d..d8cfe17b221 100644
--- a/lib/rubocop/cop/naming/constant_name.rb
+++ b/lib/rubocop/cop/naming/constant_name.rb
@@ -76,7 +76,7 @@ def allowed_conditional_expression_on_rhs?(node)
         end
 
         def contains_constant?(node)
-          node.branches.any?(&:const_type?)
+          node.branches.compact.any?(&:const_type?)
         end
       end
     end
diff --git a/spec/rubocop/cop/naming/constant_name_spec.rb b/spec/rubocop/cop/naming/constant_name_spec.rb
index f2229f999f7..b5bd69bbc80 100644
--- a/spec/rubocop/cop/naming/constant_name_spec.rb
+++ b/spec/rubocop/cop/naming/constant_name_spec.rb
@@ -114,6 +114,15 @@
     RUBY
   end
 
+  it 'does not register an offense when assigning a constant from an empty branch of `else`' do
+    expect_no_offenses(<<~RUBY)
+      CONST = if condition
+        foo
+      else
+      end
+    RUBY
+  end
+
   context 'when a rhs is a conditional expression' do
     context 'when conditional branches contain only constants' do
       it 'does not check names' do