Conteh is one of Britain's most successful boxing champions. At his peak in the mid-to-late 1970s he was considered good enough that he was touted as a possible opponent of Muhammad Ali. He enjoyed great fame in Britain and was often on the front as well as the back pages of the leading dailies due to his love of partying and women. Conteh said that his excessive lifestyle brought about a premature decline in his talents. He started boxing at age 10 at the Kirkby club that was a training ground for some of the best amateur boxers, Joey Singleton, Tucker Hetherington and Stuart Morton were only a few. At 19, he won the middleweight gold medal at the 1970 British Commonwealth Games. He won the WBC Light Heavyweight crown in October 1974 by defeating Jorge Ahumada and held the title until 1977 when he was stripped for not going through with a mandated defence. He was the loser in a fifteen round split decision to the Yugoslavian fighter Mate Parlov in an attempt to regain the title. He failed twice in further efforts to win back his old crown in 1979 and then again seven months later in 1980 - both against the American Matthew Saad Muhammad. Muhammad won both bouts but his first victory was declared void because his cornermen used an illegal substance on a cut.
He retired from professional boxing in 1980. His professional record is 34 wins, 1 draw, and 4 losses.
Conteh also has the distinction of being British Superstars competition champion in 1974, the second year of the televised sporting event. Conteh is now an after-dinner speaker and speaks at venues all across the country.
Conteh appeared on the BBC television programme Sporting Legends which was presented by Eamonn Holmes. On the show Conteh spoke at length at how he started out in the fight game and how Ali persuaded him to fight at Light-Heavyweight instead of Heavyweight as Ali believed that Conteh was too small to be a heavyweight, and how his lifestyle led to alcoholism and a charge of assault, he stated that at the time he appeared on Sporting Legends he had been dry for nine years. Conteh also made a starring appearance in the television show Boon in 1989, as a washed-up boxer. He more recently appeared on a boxing special of The Weakest Link in 2009, where he came in third place. His most recent TV acting appearance was in the crime drama "Justice", in which he again played an ex-boxer.