Brazilian driver Ayrton Senna finished second in a Lotus-Renault, with Sweden's Stefan Johansson third in a Ferrari.
Senna's result allowed him to take the lead of the Drivers' Championship from Frenchman Alain Prost, who could only manage sixth in his McLaren-TAG.
Elio de Angelis had been killed in a testing accident at Circuit Paul Ricard just over a week before the race.
Williams-Honda driver Nelson Piquet took pole late in the qualifying session using the team's spare car.
[3] Austrian Gerhard Berger scored his first front row start and the first for the BMW powered Benetton after being fastest in Friday qualifying.
Post race Mansell dedicated his win to his friend and former team mate Elio de Angelis who died just ten days prior to Spa in a testing accident at Paul Ricard.