The woman stumbled into the Manurewa RSA on Maich Rd asking for help about 8pm.
A witness told Newshub that the woman had told police she was in a van when she was stabbed, but managed to get away.
"We had a private function in the restaurant, and a young lady came through the doors covered in blood - in distress - and I could see that she had been stabbed in the neck and was bleeding profusely.
"So, we just grabbed a cloth so that we could stem the flow.
"I just knew that she needed help, and had to get on and help her. And once the ambulance took over we sort of breathed a sigh of relief and started to think about what could have gone wrong.
"Depending where that stab wound was in her neck it could have been fatal, I would think.''
Police are investigating the circumstances and no arrests have been made yet.
