Lawler - also known as 'The King' - fell unconscious while commentating on a tag-team match at the event.
WWE confirmed in an official statement: "Jerry 'The King' Lawler suffered a heart attack while commentating during last night's broadcast of Monday Night Raw in Montreal.
"We are hopeful Jerry makes a full recovery and returns to WWE in the near future. Our thoughts are with Jerry and his family."
Lawler received initial treatment from WWE medical staff and was then taken to an unnamed hospital in Montreal for further specialist assessment.
The concluding segments of Monday Night Raw aired without commentary.