The XXXI Grote Prijs van België ran over 70 laps of the 4.220-kilometre Zolder circuit, covering 295.4 kilometres. A week before the race, Stewart, Emerson Fittipaldi and Francois Cevert inspected the circuit on foot on behalf of the Grand Prix Drivers' Association and found the surface breaking up following a preceding race meeting. Stewart, Fittipaldi and Cevert refused to drive on the track in its existing state. Cevert communicated to the FIA that the drivers would seek cancellation of the event if the repair work was inadequate. The circuit owners immediately commissioned full emergency resurfacing in the week before the Grand Prix. The new tarmac held through Saturday but began disintegrating again during the race, contributing to several accidents.
Ronnie Peterson took pole position in the Lotus-Ford for the third consecutive race, posting 1:22.46. Denny Hulme (McLaren-Ford) was second, Jacky Ickx (Ferrari) third, and Cevert fourth for Tyrrell ahead of Jean-Pierre Beltoise (BRM). Stewart qualified only sixth in 1:23.28.
Cevert led from lap 2 after Hulme made a poor start, building a nine-second advantage. On lap 20, Cevert spun at the Jochen Rindt chicane, handing the lead to Fittipaldi. Stewart methodically worked through the field and took Fittipaldi on lap 24, after which the race became a Tyrrell 1-2.
Stewart won by 31.84 seconds from Cevert in 1 hour 42 minutes 13.43 seconds — his 24th Formula One victory, equalling Fangio's record. Fittipaldi was a struggling third, hampered by a fuel-pressure problem, completing his fifth podium from five rounds of 1973 but failing to win. Andrea de Adamich was a remarkable fourth in the old Brabham BT37, starting from 18th on the grid. Niki Lauda took fifth in a BRM — his first career Formula One championship points, in his ninth start. Chris Amon was sixth in the Tecno, the team's sole Formula One championship point.
Peterson, from pole, retired on lap 42 with accident damage. Jacky Ickx (Ferrari, oil pump, lap 6) and Mike Hailwood (Surtees, accident, lap 4) were early casualties. The race featured multiple accidents on the deteriorating surface, including incidents involving Jarier, Regazzoni, Beuttler and others.
Fastest lap was set by Cevert in 1:25.42 on lap 28.
After five rounds, Fittipaldi led the Drivers' Championship with 35 points, Stewart second on 28 and Cevert third on 18. Tyrrell moved ahead of Lotus in the Constructors' Championship. Lauda's emergence in mediocre BRM machinery attracted immediate attention from leading team managers.
The 1973 Belgian Grand Prix was also the last race at which Formula One teams changed their car numbers from event to event. The numbers assigned at Zolder remained fixed for the rest of the season. From 1974 onwards, numbers were allocated based on Constructors' Championship finishing positions and remained stable from year to year.