diff --git a/dev-libs/s2n/Manifest b/dev-libs/s2n/Manifest
new file mode 100644
index 0000000000..41001caae4
--- /dev/null
+++ b/dev-libs/s2n/Manifest
@@ -0,0 +1 @@
+DIST s2n-1.5.21.tar.gz 5043323 BLAKE2B d1d424ee2ea615a985f3b158ab1fd0e212e46f9774a246b9f5b184df90bd0b65f1fb3fd0c5fb2b312d0eb3194f87105121267348698e7570e9b4095a2e69f523 SHA512 faed1a4765874b91da53d3e2c6430ad14701bca45cb3e7fa9a5d1cde957ed2d7e3cc21a713d09a848e341d09f483e769a0651e15d118d2f9b8a8aa76e873b3f2
diff --git a/dev-libs/s2n/metadata.xml b/dev-libs/s2n/metadata.xml
new file mode 100644
index 0000000000..145064206e
--- /dev/null
+++ b/dev-libs/s2n/metadata.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+  <maintainer type="person">
+    <email>trakrailysurely@danceylove.net</email>
+    <name>Okamura Kazuya</name>
+  </maintainer>
+  <upstream>
+    <remote-id type="github">aws/s2n-tls</remote-id>
+  </upstream>
+</pkgmetadata>
diff --git a/dev-libs/s2n/s2n-1.5.21.ebuild b/dev-libs/s2n/s2n-1.5.21.ebuild
new file mode 100644
index 0000000000..160a91b7c0
--- /dev/null
+++ b/dev-libs/s2n/s2n-1.5.21.ebuild
@@ -0,0 +1,32 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit cmake
+
+DESCRIPTION="Simple, small, fast and secure C99 implementation of the TLS/SSL protocols"
+HOMEPAGE="https://github.com/awslabs/s2n"
+SRC_URI="https://github.com/awslabs/${PN}/archive/v${PV}.tar.gz -> ${P}.tar.gz"
+
+LICENSE="Apache-2.0"
+SLOT="0"
+KEYWORDS="~amd64"
+IUSE="test"
+
+RESTRICT="!test? ( test )"
+
+DEPEND="
+	dev-libs/openssl:=
+"
+RDEPEND="${DEPEND}"
+
+S="${WORKDIR}/${PN}-tls-${PV}"
+
+src_configure() {
+	local mycmakeargs=(
+		-DBUILD_TESTING=$(usex test)
+		-DUNSAFE_TREAT_WARNINGS_AS_ERRORS=OFF
+	)
+	cmake_src_configure
+}