diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 074a6feb48..68737fdb3f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1119,11 +1119,16 @@ jobs:
         id: mac_lib_build
         if: ${{ !cancelled() && needs.maybe-release.outputs.libs_tag && steps.mac_cli_build.outcome == 'success' }}
         shell: bash
+        env:
+          APPLE_SIMPLEX_SIGNING_KEYCHAIN: ${{ secrets.APPLE_SIMPLEX_SIGNING_KEYCHAIN }}
+          APPLE_SIMPLEX_NOTARIZATION_APPLE_ID: ${{ secrets.APPLE_SIMPLEX_NOTARIZATION_APPLE_ID }}
+          APPLE_SIMPLEX_NOTARIZATION_PASSWORD: ${{ secrets.APPLE_SIMPLEX_NOTARIZATION_PASSWORD }}
         run: |
           SKIP_VLC=1 scripts/desktop/build-lib-mac.sh
           name=simplex-chat-libs-macos-${{ matrix.arch }}
           mkdir -p release-libs/$name/libs
           find apps/multiplatform/common/src/commonMain/cpp/desktop/libs/mac-${{ matrix.arch }} -maxdepth 1 -type f -exec cp {} release-libs/$name/libs/ \;
+          scripts/ci/sign-libs-mac.sh release-libs/$name/libs
           (cd release-libs/$name && zip -r ../$name.zip libs)
 
       - name: Upload library
diff --git a/docs/contributing/RELEASES.md b/docs/contributing/RELEASES.md
index ea6123e4c8..e0b80fda5b 100644
--- a/docs/contributing/RELEASES.md
+++ b/docs/contributing/RELEASES.md
@@ -54,7 +54,7 @@ pypi.<package>.<version>    commit of the publication
 
 3. Run of `build.yml`:
    - `maybe-release`: version claimed for the commit in `releases.toml`, draft `core-<version>` created
-   - build jobs: 6 library zips uploaded
+   - build jobs: 6 library zips uploaded; macOS libraries signed with the Developer ID and notarized
    - `releases`: release published
    - `publish`: `@simplex-chat/types` published, when its version is unpublished
    - `record`: types version recorded
@@ -141,6 +141,7 @@ Versions unpublished after a failure: published by the next push to the branch.
 
 - simplex-chat-libs: release immutability enabled
 - secret `NODEJS_REPO_TOKEN`: contents of simplex-chat-libs, read and write
+- secrets `APPLE_SIMPLEX_SIGNING_KEYCHAIN`, `APPLE_SIMPLEX_NOTARIZATION_APPLE_ID` and `APPLE_SIMPLEX_NOTARIZATION_PASSWORD`: signing and notarization of the macOS libraries, shared with the desktop app build
 - trusted publisher of `simplex-chat` and `@simplex-chat/types` on npm and of `simplex-chat` on PyPI: workflow `build.yml`
 - secrets `NPM_TOKEN` and `PYPI_API_TOKEN`: used instead of trusted publishing when set
 - variables `NPM_SCOPE`, `PYPI_PROJECT`, `PYPI_URL` and `PYPI_UPLOAD_URL`: publication under other names, for test repositories
diff --git a/scripts/ci/sign-libs-mac.sh b/scripts/ci/sign-libs-mac.sh
new file mode 100755
index 0000000000..e455404503
--- /dev/null
+++ b/scripts/ci/sign-libs-mac.sh
@@ -0,0 +1,31 @@
+#!/bin/bash
+
+set -euo pipefail
+
+libs=$1
+team=5NN7GUYB6T
+keychain=/tmp/simplex.keychain
+temp=$(mktemp -d)
+trap 'rm -rf "$keychain" "$temp"' EXIT
+
+notarytool() {
+  xcrun notarytool "$@" --apple-id "$APPLE_SIMPLEX_NOTARIZATION_APPLE_ID" --password "$APPLE_SIMPLEX_NOTARIZATION_PASSWORD" --team-id "$team"
+}
+
+echo "$APPLE_SIMPLEX_SIGNING_KEYCHAIN" | base64 --decode -o "$keychain"
+security unlock-keychain -p "" "$keychain"
+security list-keychains -s $(security list-keychains | xargs) "$keychain"
+
+for lib in "$libs"/*.dylib; do
+  codesign --remove-signature "$lib"
+  codesign --timestamp --options runtime --force --sign "Developer ID Application: SimpleX Chat Ltd ($team)" --keychain "$keychain" "$lib"
+done
+
+ditto -c -k --keepParent "$libs" "$temp/libs.zip"
+notarytool submit "$temp/libs.zip" --wait --timeout 1h --output-format json > "$temp/submission.json" || true
+cat "$temp/submission.json"
+read -r id status < <(python3 -c 'import json, sys; r = json.load(open(sys.argv[1])); print(r["id"], r["status"])' "$temp/submission.json")
+notarytool log "$id"
+if [ "$status" != Accepted ]; then
+  exit 1
+fi