diff --git a/.github/workflows/custom-release.yml b/.github/workflows/custom-release.yml
index a962291d5..bb12cd21e 100644
--- a/.github/workflows/custom-release.yml
+++ b/.github/workflows/custom-release.yml
@@ -48,6 +48,53 @@ jobs:
         env:
           SYNC_REMOTE: origin
 
+      - name: Import Developer ID certificate
+        run: |
+          set -euo pipefail
+          keychain_path="$RUNNER_TEMP/syncthing-release-signing.keychain-db"
+          keychain_password="$(openssl rand -hex 24)"
+          certificate_path="$RUNNER_TEMP/developer-id-application.p12"
+          previous_default_keychain="$(security default-keychain -d user 2>/dev/null | sed 's/[ "]//g' || true)"
+
+          echo "CUSTOM_RELEASE_KEYCHAIN_PATH=$keychain_path" >> "$GITHUB_ENV"
+          echo "CUSTOM_RELEASE_KEYCHAIN_PASSWORD=$keychain_password" >> "$GITHUB_ENV"
+          echo "CUSTOM_RELEASE_CERTIFICATE_PATH=$certificate_path" >> "$GITHUB_ENV"
+          echo "CUSTOM_RELEASE_PREVIOUS_DEFAULT_KEYCHAIN=$previous_default_keychain" >> "$GITHUB_ENV"
+
+          if [ -z "$DEVELOPER_ID_APPLICATION_P12_BASE64" ]; then
+            echo "DEVELOPER_ID_APPLICATION_P12_BASE64 secret is required" >&2
+            exit 1
+          fi
+          if [ -z "$DEVELOPER_ID_APPLICATION_P12_PASSWORD" ]; then
+            echo "DEVELOPER_ID_APPLICATION_P12_PASSWORD secret is required" >&2
+            exit 1
+          fi
+
+          printf '%s' "$DEVELOPER_ID_APPLICATION_P12_BASE64" | base64 -D > "$certificate_path"
+          security create-keychain -p "$keychain_password" "$keychain_path"
+          security set-keychain-settings -lut 21600 "$keychain_path"
+          security unlock-keychain -p "$keychain_password" "$keychain_path"
+          security import "$certificate_path" -k "$keychain_path" -P "$DEVELOPER_ID_APPLICATION_P12_PASSWORD" -A -T /usr/bin/codesign -T /usr/bin/security
+          security list-keychains -d user -s "$keychain_path"
+          security default-keychain -d user -s "$keychain_path"
+          security set-key-partition-list -S apple-tool:,apple:,codesign: -s -k "$keychain_password" "$keychain_path"
+
+          identity_output="$(security find-identity -v -p codesigning "$keychain_path")"
+          printf '%s\n' "$identity_output"
+          codesign_identity="$(printf '%s\n' "$identity_output" | sed -n 's/.*"\(Developer ID Application:[^"]*\)".*/\1/p' | head -n 1)"
+          if [ -z "$codesign_identity" ]; then
+            echo "Developer ID Application signing identity is required in DEVELOPER_ID_APPLICATION_P12_BASE64" >&2
+            exit 1
+          fi
+
+          probe_binary="$RUNNER_TEMP/codesign-probe"
+          cp /usr/bin/true "$probe_binary"
+          codesign --force --dryrun --sign "$codesign_identity" --keychain "$keychain_path" --options runtime --timestamp "$probe_binary"
+          echo "CUSTOM_RELEASE_CODESIGN_IDENTITY=$codesign_identity" >> "$GITHUB_ENV"
+        env:
+          DEVELOPER_ID_APPLICATION_P12_BASE64: ${{ secrets.DEVELOPER_ID_APPLICATION_P12_BASE64 }}
+          DEVELOPER_ID_APPLICATION_P12_PASSWORD: ${{ secrets.DEVELOPER_ID_APPLICATION_P12_PASSWORD }}
+
       - name: Build patched Syncthing release
         run: |
           case "$(uname -m)" in
@@ -63,7 +110,9 @@ jobs:
           CUSTOM_RELEASE_PUSH: "1"
           CUSTOM_RELEASE_PUSH_BRANCH: "0"
           CUSTOM_RELEASE_REMOTE: origin
-          CUSTOM_RELEASE_SIGN_DARWIN: "0"
+          CUSTOM_RELEASE_CODESIGN_TEAM_ID: "NG5W75WE8U"
+          CUSTOM_RELEASE_SIGN_DARWIN: "1"
+          CUSTOM_RELEASE_REQUIRE_GATEKEEPER_ASSESSMENT: "0"
           CUSTOM_RELEASE_CREATE_GITEA_RELEASE: "0"
           GH_TOKEN: ${{ github.token }}
 
@@ -85,3 +134,16 @@ jobs:
           CUSTOM_RELEASE_UPSTREAM_TAG: ${{ github.event.inputs.upstream_tag }}
           CUSTOM_RELEASE_SUFFIX: ${{ github.event.inputs.suffix || 'stignore.7' }}
           GH_TOKEN: ${{ github.token }}
+
+      - name: Delete temporary keychain
+        if: always()
+        run: |
+          if [ -n "${CUSTOM_RELEASE_PREVIOUS_DEFAULT_KEYCHAIN:-}" ] && [ -e "$CUSTOM_RELEASE_PREVIOUS_DEFAULT_KEYCHAIN" ]; then
+            security default-keychain -d user -s "$CUSTOM_RELEASE_PREVIOUS_DEFAULT_KEYCHAIN" || true
+          fi
+          if [ -n "${CUSTOM_RELEASE_KEYCHAIN_PATH:-}" ]; then
+            security delete-keychain "$CUSTOM_RELEASE_KEYCHAIN_PATH" || true
+          fi
+          if [ -n "${CUSTOM_RELEASE_CERTIFICATE_PATH:-}" ]; then
+            rm -f "$CUSTOM_RELEASE_CERTIFICATE_PATH"
+          fi
diff --git a/patches/README.md b/patches/README.md
index d6930ea9b..6384d1e03 100644
--- a/patches/README.md
+++ b/patches/README.md
@@ -41,9 +41,8 @@ matching custom tag already exists, pushes only the `<upstream>-stignore.7` tag
 by default, and publishes release assets on the CI host running the workflow.
 The local `custom/<version>` branch is only pushed when
 `CUSTOM_RELEASE_PUSH_BRANCH=1` is set. The workflow builds macOS arm64, Linux
-amd64, and Linux arm64 archives. Gitea signs its macOS build with the configured
-Developer ID certificate; GitHub builds an unsigned macOS archive until the
-equivalent signing secrets are configured there.
+amd64, and Linux arm64 archives. Both hosts sign their macOS builds with their
+configured Developer ID certificate.
 
 The patch makes root-level `.stignore` sync like regular folder content while
 keeping `.stfolder` and `.stversions` protected as internal Syncthing paths.
diff --git a/scripts/tests/test-custom-release-macos-runner.bats b/scripts/tests/test-custom-release-macos-runner.bats
index 1f9b8baf1..f186219ae 100644
--- a/scripts/tests/test-custom-release-macos-runner.bats
+++ b/scripts/tests/test-custom-release-macos-runner.bats
@@ -30,13 +30,33 @@ setup() {
 	run rg -n 'CUSTOM_RELEASE_CREATE_GITEA_RELEASE: "0"' "$GITHUB_WORKFLOW"
 	[ "$status" -eq 0 ]
 
-	run rg -n 'CUSTOM_RELEASE_SIGN_DARWIN: "0"' "$GITHUB_WORKFLOW"
+	run rg -n 'CUSTOM_RELEASE_SIGN_DARWIN: "1"' "$GITHUB_WORKFLOW"
 	[ "$status" -eq 0 ]
 
 	run rg -n 'tea|ffmini_macos_arm64' "$GITHUB_WORKFLOW"
 	[ "$status" -ne 0 ]
 }
 
+@test "github imports signing secrets into a disposable keychain" {
+	run rg -n 'DEVELOPER_ID_APPLICATION_P12_BASE64:.*secrets.DEVELOPER_ID_APPLICATION_P12_BASE64' "$GITHUB_WORKFLOW"
+	[ "$status" -eq 0 ]
+
+	run rg -n 'DEVELOPER_ID_APPLICATION_P12_PASSWORD:.*secrets.DEVELOPER_ID_APPLICATION_P12_PASSWORD' "$GITHUB_WORKFLOW"
+	[ "$status" -eq 0 ]
+
+	run rg -n 'security import .* -P "\$DEVELOPER_ID_APPLICATION_P12_PASSWORD"' "$GITHUB_WORKFLOW"
+	[ "$status" -eq 0 ]
+
+	run rg -n 'if: always\(\)' "$GITHUB_WORKFLOW"
+	[ "$status" -eq 0 ]
+
+	run rg -n 'security delete-keychain "\$CUSTOM_RELEASE_KEYCHAIN_PATH"' "$GITHUB_WORKFLOW"
+	[ "$status" -eq 0 ]
+
+	run rg -n 'rm -f "\$CUSTOM_RELEASE_CERTIFICATE_PATH"' "$GITHUB_WORKFLOW"
+	[ "$status" -eq 0 ]
+}
+
 @test "custom release runs as one job on ffmini macos runner" {
 	run rg -n 'runs-on:[[:space:]]*ffmini_macos_arm64' "$WORKFLOW"
 	[ "$status" -eq 0 ]