Emergency services were called to the Marriott hotel in Dyce, Aberdeen, at around 10.50pm on Saturday.
The man was taken to Aberdeen Royal Infirmary where he is in a serious condition.
It is not known how he was injured, and police have launched an investigation.
Sergeant Rory Campbell said: “Enquiries are currently ongoing into the circumstances surrounding how this man came to be injured - further information will be issued in due course if necessary.
“I would like to thank all those who have helped with our enquiries so far and to staff at the hotel for their assistance.”