Police were called to an apartment at the intersection of George-V and Pierre-de-Coubertin avenues at around 3:30 a.m.
The man had been stabbed with a knife.
Investigators are meeting with a 26-year-old man to determine his role in the incident.
It's the third homicide of the year in Montreal.
In a separate incident, a man was fatally shot early this morning in Montreal's Rosemont neighbourhood in the city's fourth homicide of the year.