The airport confirmed on X that an "incident" occurred on Monday with the Delta Airlines flight from Minneapolis and that all passengers and crew were accounted for.
One passenger was critically injured and seven others were also hurt, paramedics said.
Video from the scene showed the Mitsubishi CRJ-900LR upside down on the snowy tarmac as emergency workers hosed it down.
The plane was partly obscured by snow from a winter storm that hit Toronto at the weekend.
Ornge air ambulance said it was transporting one young patient to Toronto's SickKids Hospital and two adults with critical injuries to other hospitals in the city.
"Emergency teams are responding," the airport said in a post on the social platform X.
"All passengers and crew are accounted for."
It is too early to say what caused the plane to turn over, but weather might have played a factor.
According to the Meteorological Service of Canada, the airport was experiencing blowing snow and winds of 50km/h gusting to 65km/h.
The temperature was about minus 8.6C.
The Federal Aviation Administration said the Transportation Safety Board of Canada would lead the investigation and provide updates.
It is at least the fourth major aviation mishap in North America in the past month.
A commercial jetliner and an army helicopter collided near Washington DC on January 29, killing 67 people, a medical transport plane crashed in Philadelphia on January 31, killing the six people on board and another person on the ground, and 10 were killed in a plane crash in Alaska.
Delta said it was "aware of reports of Endeavour Flight 4819 operating from Minneapolis-St Paul to Toronto-Pearson International Airport as involved in an incident".
Endeavour Air, based in Minneapolis, is a subsidiary of Delta Air Lines and the world's largest operator of CRJ-900 aircraft.
The airline operates 130 regional jets on 700 daily flights to more than 126 cities in the US, Canada and the Caribbean, according to the company's website.
The CRJ900, a popular regional jet, was developed by Canadian aerospace company Bombardier.
It is in the same family of aircraft as the CRJ700, the type of plane involved in the midair collision near Reagan National Airport on January 29.
Ontario Premier Doug Ford said on X he was "relieved there are no casualties after the incident at Toronto Pearson".
"Provincial officials are in contact with the airport and local authorities and will provide any help that's needed," he added.
Toronto is the capital of Ontario province.
15°C