The 16-year-old was found with serious injuries in a courtyard on Prince Edward Street, in Govanhill on Glasgow's south side, at about 12.40am this morning.
Police were alerted to a disturbance in the area and discovered the teenager.
He was taken to the Victoria Infirmary, where he was being treated for his injuries today. Hospital staff described his condition as "serious".
Detective Inspector Ian Hylands said: "We are treating this assault as attempted murder and enquires are on-going to establish what exactly happened prior to the injured man being discovered.
"Officers are carrying out door-to-door enquiries in the nearby neighbourhood and examining CCTV footage in an effort to trace those responsible for this vicious attack.
"I'd like to speak to anyone who witnessed a disturbance in the Prince Edward Street area just before 12.40am or anyone has any information that could help identify the person or persons responsible."