Walker is best known for winning the Olympic Games 1500 metres in 1976. Unfortunately, this achievement was somewhat overshadowed because 22 African countries boycotted the games to protest against a tour of South Africa by the New Zealand national rugby team.
The record lasted until July 17, 1979, when it was beaten by Sebastian Coe. Walker later became the first to run 100 sub 4 minute miles during his career. In 1996, Walker announced that he had Parkinson's disease.