Jackson won his first major medal, a silver, in the 110 m hurdles, aged nineteen at the 1986 Commonwealth Games. He soon established himself on the global scene, taking bronze at the 1987 World Championships in Athletics and a silver medal at the 1988 Summer Olympics. After winning another silver in the 60 metres hurdles at the 1989 IAAF World Indoor Championships, he won European and Commonwealth gold medals in 1990. The 1993 season saw him reach the pinnacle of his sport: after a silver at the 1993 Indoor Worlds, he went on to set a world record of 12.91 seconds to become the 1993 World Champion. This mark was unbeaten for almost thirteen years and remains the world championship record. Jackson also helped the British 4×100 metres relay team to the world silver medal.