diff --git a/clang-tools-extra/clang-tidy/add_new_check.py b/clang-tools-extra/clang-tidy/add_new_check.py
--- a/clang-tools-extra/clang-tidy/add_new_check.py
+++ b/clang-tools-extra/clang-tidy/add_new_check.py
@@ -77,9 +77,7 @@
 
 #include "../ClangTidyCheck.h"
 
-namespace clang {
-namespace tidy {
-namespace %(namespace)s {
+namespace clang::tidy::%(namespace)s {
 
 /// FIXME: Write a short description.
 ///
@@ -93,9 +91,7 @@
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
 };
 
-} // namespace %(namespace)s
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::%(namespace)s
 
 #endif // %(header_guard)s
 """ % {'header_guard': header_guard,
@@ -129,9 +125,7 @@
 
 using namespace clang::ast_matchers;
 
-namespace clang {
-namespace tidy {
-namespace %(namespace)s {
+namespace clang::tidy::%(namespace)s {
 
 void %(check_name)s::registerMatchers(MatchFinder *Finder) {
   // FIXME: Add matchers.
@@ -149,9 +143,7 @@
       << FixItHint::CreateInsertion(MatchedDecl->getLocation(), "awesome_");
 }
 
-} // namespace %(namespace)s
-} // namespace tidy
-} // namespace clang
+} // namespace clang::tidy::%(namespace)s
 """ % {'check_name': check_name_camel,
        'module': module,
        'namespace': namespace})
diff --git a/clang-tools-extra/clang-tidy/rename_check.py b/clang-tools-extra/clang-tidy/rename_check.py
--- a/clang-tools-extra/clang-tidy/rename_check.py
+++ b/clang-tools-extra/clang-tidy/rename_check.py
@@ -308,8 +308,13 @@
     for filename in check_implementation_files:
       # Move check implementation to the directory of the new module.
       filename = fileRename(filename, old_module_path, new_module_path)
+      # TODO: remove below replacement when all clang-tidy checks have been
+      # updated with C++17 nested namespaces.
       replaceInFileRegex(filename, 'namespace ' + old_module + '[^ \n]*',
                          'namespace ' + new_namespace)
+      replaceInFileRegex(filename,
+                         'namespace clang::tidy::' + old_module + '[^ \n]*',
+                         'namespace clang::tidy::' + new_namespace)
 
   if (args.old_check_name == args.new_check_name):
     return
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -106,6 +106,8 @@
   which is no longer in use. The option will be fully removed in
   :program:`clang-tidy` version 18.
 
+- Use C++17 nested namespaces in `add_new_check.py` and `rename_check.py`.
+
 New checks
 ^^^^^^^^^^