As the Mont-Tremblant circuit had been closed down because of a dispute with the local racing authorities the Canadian Grand Prix settled at an upgraded Mosport Park. There was a big field as usual. Team Lotus had replaced Dave Walker with Reine Wisell, while the Swede's drive in the fourth BRM had gone to local hero Bill Brack while Skip Barber turned up in a Gene Mason Racing March 711.

Qualifying resulted in pole position for Peter Revson's McLaren with Denny Hulme alongside, the team having an advantage because of the knowledge of the track gained from CanAm races. The front row was completed by Ronnie Peterson's March. The new World Champion Emerson Fittipaldi was on the second row with his predecessor Jackie Stewart alongside. The third row featured François Cévert (Tyrrell) and the Ferraris of Clay Regazzoni and Jacky Ickx while the top 10 was completed by Carlos Reutemann's Brabham and Chris Amon's Matra. The job of being best of the rest went on this occasion to Brabham's Wilson Fittipaldi.

There was a fog on race morning and the start of the race had to be delayed. When the weather cleared a bit Peterson took the lead with Stewart moving up to second ahead of Revson. Hulme dropped right into the midfield.

Peterson stayed ahead until the fourth lap when he made a mistake and Stewart was able to get ahead of begin to pull away. Further back Ickx passed Revson although the American was later able to get the place back as the Ferrari began to lose power. Ickx faded quickly behind Fittipaldi and Regazzoni. The order remained largely unchanged until lap 54 when Peterson was trying to lap Graham Hill. The Brabham driver refused to get out of the way and the two cars collided, the March suffering a bent steering. Peterson stopped not far from the exit of the pits and pushed the car back to the garages. He rejoined but was disqualified. This left Revson and Fittipaldi fighting for second place but a challenge from Emerson resulted in him damaging his front wing and he dropped back and had to pit. This left Regazzoni in third place but he stumbled over Barber in the closing laps and so was overtaken by Reutemann and Hulme. The McLaren driver managed to get ahead when Reutemann ran out of fuel at the end of the race. Stewart thus ended up on the podium with the two McLaren drivers with Revson second and Hulme third.