diff --git a/CHANGELOG.md b/CHANGELOG.md
index f75b263f..a6152bfa 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,8 @@ Note: In this file, do not use the hard wrap in the middle of a sentence for com
 
 ## [Unreleased]
 
+## [2.78.0] - 2026-05-14
+
 - Support `cargo-mutants`. ([#1812](https://github.com/taiki-e/install-action/pull/1812), thanks @jakewimmer)
 
 - Update `covgate@latest` to 0.2.0.
@@ -6538,7 +6540,8 @@ Note: This release is considered a breaking change because installing on version
 
 Initial release
 
-[Unreleased]: https://github.com/taiki-e/install-action/compare/v2.77.7...HEAD
+[Unreleased]: https://github.com/taiki-e/install-action/compare/v2.78.0...HEAD
+[2.78.0]: https://github.com/taiki-e/install-action/compare/v2.77.7...v2.78.0
 [2.77.7]: https://github.com/taiki-e/install-action/compare/v2.77.6...v2.77.7
 [2.77.6]: https://github.com/taiki-e/install-action/compare/v2.77.5...v2.77.6
 [2.77.5]: https://github.com/taiki-e/install-action/compare/v2.77.4...v2.77.5