One of England's strongest players, and once in the world's top ten, Nunn has won several individual gold medals at Chess Olympiads.

As well as being a strong player, Nunn is regarded as one of the best contemporary authors of chess books. He has penned many volumes, including Secrets of Grandmaster Chess which won the British Chess Federation Book of the Year award in 1988 and John Nunn's Best Games which took the award in 1995. He is the director of chess publishers Gambit Publications.

Nunn is also involved with chess problems, composing several examples and solving as part of the British team on several occasions. On this subject he wrote Solving in Style (1985).