Malcolm competed in three Paralympics in 1996, 2000 and 2004. In each games he won the gold medal in the 800m. In the 1996 games he also won silvers in the 1500m and 400m. In the 2000 games he won a bronze in the 400m and competed as part of the South Africa 4 × 100 m team. In his final games he won his second 400m silver as well as competing in the 200m and the 4 × 100 m.