In the early hours of Sunday morning, a group of young adults were walking together along Chapman Road (near McDonalds).
The group was approached by a man who, according to Police "aggressively conversed" with a female within the group.
One young man in the group stepped in to assist the female. Police say the man who approached the group then became aggressive to the young man in the group and struck him in the face.
The attack caused extensive injuries around the mouth and jaw.
Inquiries are continuing by Geraldton Detectives.