The incident took place after the victim left a friend's flat in Argyle Street at about 18:30 on Friday.
He returned to the flat at about 01:20 on Saturday, having suffered a stab wound and a head injury. He was taken to the Royal Alexandra Hospital for treatment.
Police are treating the incident as attempted murder.
Officers have been searching the area around Argyle Street to establish the location of the attack.
Detectives are also gathering any available CCTV footage which could assist their inquiries.
Det Sgt Ian Ross said: "Our inquiries are at an early stage and we are trying to establish the man's movements after he left the flat on Friday evening.
"The man has suffered a violent attack and we need to piece together where he went and who he saw.
"This information will assist our investigation as we try to trace the person or people responsible for his attack.
"I am appealing to members of the local community to contact us with any information or knowledge they may have.
"It's vital we find out exactly what happened to this man and why."
A 33-year-old man has suffered life-threatening injuries following a "violent attack" in Paisley.