Mafe was born in Isleworth, London. At the 200 metres, he won the gold medal at the 1989 European Indoor Championships in 20.92; silver at the 1985 IAAF World Indoor Games in 20.96 and a silver at the 1989 World Indoor Championships in 20.87. He represented England and won a bronze medal in the 200 metres event, at the 1990 Commonwealth Games in Auckland, New Zealand, in 20.26 (w).. He reached the final of 200 metres at the 1984 Olympic Games, where he finished eighth.