Police were called to the incident, in Cheddar, at about 0200 GMT on New Year's Day.
The man was taken by police helicopter to Frenchay Hospital in Bristol where he later died.
A 20-year-old man has been arrested in connection with the attack and remains in police custody. Police appealed for witnesses.
Det Insp Guy Turner said: "We know there were people in the area at this time following New Year's celebrations.
"It is imperative we speak to these people as they may have information that could be vital to this investigation."
