The 19-year-old, who worked at the five-star Blythswood Square, had been at a party thrown by a former employee when he fell and landed on spiked metal railings in West George Street at around 5am on Wednesday.
The friend had booked the £1,500-a-night suite, where celebrities such as Beyonce and P.Diddy have reportedly previously stayed.
Emergency services were called after the man was found on the pavement.
A foot-long spike from metal railings was found nearby.
He is being treated at Glasgow Royal Infirmary.
Inspector Kenny Darroch said: "He's alive, but he has horrendous injuries."
Hans Rissmann, managing director at Blythswood Square, said the thoughts of all the young man's colleagues were with him and his family.
He said: "Contact has been made with his relatives. Everyone's thoughts are with them.
"The hotel is providing every co-operation to the authorities.
"A full inquiry will be undertaken in order to understand the circumstances surrounding this accident."
A student whose room overlooked the scene said: "I woke up and the place was swarming with police.
"I asked the hotel what was happening and they said there had been an accident. I assumed it was a car accident.
"I was so shocked when I found out what actually happened. It's horrible."