The man is said to be possibly aged between 25 and 40.
He has dark hair and tanned/olive skin. He has dark facial hair around his mouth and chin.
There are no visible tattoos on the front of his body, police said.
Senior Sergeant Amber Stobie, of Counties Manukau Police, said: "Police want to locate and speak with his next-of-kin urgently and while we understand this is a limited description, we are hoping someone might have information that will help us to identify him - or know someone who is missing from overnight who fits a similar description."
The driver involved in the incident is assisting police with their inquiries and being supported, Stobie said.