A former English Amateur Championship and World Amateur Championship finalist, Johnson turned professional in 1979, and after several years as an unranked player, reached the final of the 1983 Professional Players Tournament, where he narrowly lost 8–9 to Tony Knowles. In 1986, as a massive underdog, he defeated Steve Davis 18–12 to win the 1986 World Snooker Championship. The following year, he reached the final again, losing 14–18 to Davis; as a result coming closer to breaking the Crucible curse than any other player.