I lost days to this, but finally found a solution. https://stackoverflow.com/questions/47582989/launchd-not-able-to-access-mac-os-keychains Add this to your plist <key>SessionCreate</key> <true/> Our LaunchDaemon can run xcode builds, and finds a valid identity to sign with now. Also had to add the Apple Worlwide Developer Relation cert to the system keychain if [ ! -f ./AppleWWDRCAG3.cer ]; then echo "Downloadind Apple Worlwide Developer Relation GA3 certificate" curl -s -o ./AppleWWDRCAG3.cer https://www.apple.com/certificateauthority/AppleWWDRCAG3.cer fi echo "Installing Apple Worlwide Developer Relation GA3 certificate into System keychain" SYSTEM_KEYCHAIN=/Library/Keychains/System.keychain sudo security import ./AppleWWDRCAG3.cer -t cert -k "${SYSTEM_KEYCHAIN}"