diff --git a/CHANGELOG.md b/CHANGELOG.md
index 333a689e639..44f5f99b49b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,33 @@
+# OP-TEE - version 4.0.0 (2023-10-20)
+
+- Links to the release pages, commits and pull requests merged into this release for:
+  - OP-TEE/optee_os: [release page][OP_TEE_optee_os_release_4_0], [commits][OP_TEE_optee_os_commits_4_0] and [pull requests][OP_TEE_optee_os_pr_4_0]
+  - OP-TEE/optee_client: [release page][OP_TEE_optee_client_release_4_0], [commits][OP_TEE_optee_client_commits_4_0] and [pull requests][OP_TEE_optee_client_pr_4_0]
+  - OP-TEE/optee_test: [release page][OP_TEE_optee_test_release_4_0], [commits][OP_TEE_optee_test_commits_4_0] and [pull requests][OP_TEE_optee_test_pr_4_0]
+  - OP-TEE/build: [release page][OP_TEE_build_release_4_0], [commits][OP_TEE_build_commits_4_0] and [pull requests][OP_TEE_build_pr_4_0]
+  - linaro-swg/optee_examples: [release page][linaro_swg_optee_examples_release_4_0], [commits][linaro_swg_optee_examples_commits_4_0] and [pull requests][linaro_swg_optee_examples_pr_4_0]
+
+
+[OP_TEE_optee_os_release_4_0]: https://github.com/OP-TEE/optee_os/releases/tag/4.0.0
+[OP_TEE_optee_os_commits_4_0]: https://github.com/OP-TEE/optee_os/compare/3.22.0...4.0.0
+[OP_TEE_optee_os_pr_4_0]: https://github.com/OP-TEE/optee_os/pulls?q=is%3Apr+is%3Amerged+base%3Amaster+merged%3A..2023-10-20
+
+[OP_TEE_optee_client_release_4_0]: https://github.com/OP-TEE/optee_client/releases/tag/4.0.0
+[OP_TEE_optee_client_commits_4_0]: https://github.com/OP-TEE/optee_client/compare/3.22.0...4.0.0
+[OP_TEE_optee_client_pr_4_0]: https://github.com/OP-TEE/optee_client/pulls?q=is%3Apr+is%3Amerged+base%3Amaster+merged%3A..2023-10-20
+
+[OP_TEE_optee_test_release_4_0]: https://github.com/OP-TEE/optee_test/releases/tag/4.0.0
+[OP_TEE_optee_test_commits_4_0]: https://github.com/OP-TEE/optee_test/compare/3.22.0...4.0.0
+[OP_TEE_optee_test_pr_4_0]: https://github.com/OP-TEE/optee_test/pulls?q=is%3Apr+is%3Amerged+base%3Amaster+merged%3A..2023-10-20
+
+[OP_TEE_build_release_4_0]: https://github.com/OP-TEE/build/releases/tag/4.0.0
+[OP_TEE_build_commits_4_0]: https://github.com/OP-TEE/build/compare/3.22.0...4.0.0
+[OP_TEE_build_pr_4_0]: https://github.com/OP-TEE/build/pulls?q=is%3Apr+is%3Amerged+base%3Amaster+merged%3A..2023-10-20
+
+[linaro_swg_optee_examples_release_4_0]: https://github.com/linaro-swg/optee_examples/releases/tag/4.0.0
+[linaro_swg_optee_examples_commits_4_0]: https://github.com/linaro-swg/optee_examples/compare/3.22.0...4.0.0
+[linaro_swg_optee_examples_pr_4_0]: https://github.com/linaro-swg/optee_examples/pulls?q=is%3Apr+is%3Amerged+base%3Amaster+merged%3A..2023-10-20
+
 # OP-TEE - version 3.22 (2023-07-07)
 
 - Links to the release pages, commits and pull requests merged into this release for:
diff --git a/mk/config.mk b/mk/config.mk
index 8aed0995f1e..a9a68e3a48d 100644
--- a/mk/config.mk
+++ b/mk/config.mk
@@ -120,8 +120,8 @@ CFG_OS_REV_REPORTS_GIT_SHA1 ?= y
 # we might be outside of a Git environment, or the tree may have been cloned
 # with limited depth not including any tag, so there is really no guarantee
 # that TEE_IMPL_VERSION contains the major and minor revision numbers.
-CFG_OPTEE_REVISION_MAJOR ?= 3
-CFG_OPTEE_REVISION_MINOR ?= 22
+CFG_OPTEE_REVISION_MAJOR ?= 4
+CFG_OPTEE_REVISION_MINOR ?= 0
 CFG_OPTEE_REVISION_EXTRA ?=
 
 # Trusted OS implementation version