Anthony Condron, 29, had been enjoying a night out with his girlfriend and friends when he was targeted in an "unprovoked" assault at Maya Bar in the city centre, police said.
Emergency crews were called and he was taken to hospital but died shortly before 2.30am on Saturday.
Merseyside Police said a 22-year-old man from Liverpool, a 24-year-old man from Aigburth and a 23-year-old man from Mossley Hill are being questioned on suspicion of murder.
Detectives have appealed for information from anyone who was in Maya Bar in the early hours of Saturday.
They particularly want to speak to a group of girls who are thought to have been in the bar area at the time of the incident.
The family of Mr Condron, from Huyton, are being supported by specially trained officers, police said.
Following Mr Condron's death, Detective Chief Inspector Mark Tivendale said: "This was an unprovoked attack on a young male enjoying a night out with his girlfriend and friends, which has tragically resulted in the loss of his life."
