Edwon Anastacio Freitas D’Ascensao attacked the other man in Havana nightclub at around 01:00 on 24 September 2023.
He left the victim with lacerations to his forehead that required hospital treatment.
D’Ascensao pleaded guilty to grave and criminal assault.
St Helier Centenier Paul Huelin, prosecuting, said the victim had also missed a day at work because of the injury.
Advocate Stephen Waughope, defending, said D’Ascensao had chosen to plead guilty despite the fact that there was no CCTV or testimony from witnesses to confirm his guilt.
“That guilty plea is of great assistance,” he said.
Relief Magistrate David Le Cornu told D’Ascensao: “I accept you have shown remorse and you have good work record. But your criminal record is mounting up.”
He sentenced D’Ascensao to 90 hours of community service due to his guilty plea, remorse and youth – but added: “Let’s hope you learn from this.
“If you keep coming back to court you will inevitably receive a custodial sentence.”