Detectives are hunting the thug who attacked the 18-year-old at The Tunnel early on Sunday.
It is understood the attacker sliced off part of the teenager's ear with a blade at the city centre nightspot.
Police have appealed to clubbers, who may hold the key to catching the attacker.
Officers want party-goers who were in the Mitchell Street venue at the time of the attack to come forward.
Emergency services raced to the scene and the victim was taken to Glasgow Royal Infirmary.
He received treatment for a facial injury before being released.
Police said extensive inquiries were underway to trace the thug reponsible.
The attack happened at around 3.30am on Sunday.
Detective Constable Murray Owen, who is leading the investigation, urged any revellers who may have witnessed the incident to come forward.
He said: "Police were called to The Tunnel nightclub at around 3.30am on Sunday March 30.
"An 18-year-old man was taken to the Glasgow Royal Infirmary.
"He was treated for a facial injury before being released."
Police believe they may have information that will help catch the attacker, who is believed to have left The Tunnel shortly after the incident.
Officers are also carrying local inquiries and reviewing CCTV in a bid to catch him.
DC Murray Owen, who is based at the City Centre Police Office, said: "I would ask anyone who has any information about the incident to come forward and contact police."
Anyone with any information is asked to contact Police Scotland on 101.