To defend himself from a bully when he was a teenager Nojim Maiyegun began training as a boxer at his local gym. The hard work paid off with Maiyegun eventually going on to represent the Nigerian national boxing team. He fought in his first international fight in 1960 and competed in multiple tournaments in Africa over the next couple of years. By 1964 the light-middleweight had been called up to the Olympic team to fight at the Tokyo Games. Maiyegun defeated Bill Robinson (GBR) and Tom Bogs (DEN) before losing to Joseph Gonzales (FRA) in the semi-finals. This resulted in him winning bronze to become the first athlete representing Nigeria to win a medal at the Olympics. Two years later he won bronze at the 1966 British Empire and Commonwealth Games in Kingston, Jamaica.
In 1969 Maiyegun turned professional and recorded 15 wins in his home country. By early 1971 he had relocated to Austria where he fought a further 16 professional bouts across Europe, winning 12 of those. By the time of his final fight in December 1973 in Wien, which he lost on points, he was already losing his sight. Maiyegun retired from the ring and then worked as a janitor and a street cleaner before becoming completely blind.