New South Wales police say that two men became involved in an altercation in the bar on Goulburn Street, Sydney.
During the incident, one of the men allegedly threw a glass at the other man, causing fragments of it to become embedded in his skull.
Security staff intervened before emergency services were alerted.
The 20-year-old injured man was rushed to the city's St Vincent's Hospital for treatment.
A 32-year-old Irishman was arrested at the pub and taken to City Central Police Station where he was charged with reckless wounding.
He was given conditional bail to appear in court on February 19.