Officers said that the 35-year-old victim was approached and attacked by a group of four or five men aged around 18 to 20.
The incident took place between 6pm and 8pm on Monday, June 28 at the rear of Balgrayhill Community Centre in the Springburn area.
The man sustained serious injuries and was treated at Glasgow Royal Infirmary.
Detective Constable Peter Lagan of Maryhill CID said: “This appears to have been an unprovoked attack which has left a man with serious facial injuries after he was punched and kicked.
“I am appealing to anyone in the area at the time who may have seen something to come forward. Also, if anyone was driving and may have captured footage on dashcam that could help with our inquiries, please get in touch.”