Police said someone found a man in his 40s around 11:40 a.m. on Wednesday.
Urgences-santé said the victim was stabbed repeatedly with a machete and sustained injuries to most of his body.
"He sustained several lacerations on his body from his head down to his stomach, down to his legs and arms," said spokesman David Sasson. "During the intervention, he was conscious and talking to the paramedics. However, during transport he was in cardiac arrest while he was on the way to the hospital."
The victim was pronounced dead at the hospital.
The incident happened at 4121 51st Street near Pix IX Boulevard.
Police have blocked off a section of the street and set up a safety perimeter around the apartment building.
Const. Daniel Richer said police are talking with possible witnesses and neighbours.
This is Montreal's third homicide of the year.