Born in Bristol, Belcher beat Paddington Tom Jones in April 1799 in the Middleweight Championship of England. He drew with champion Jack Bartholomew in a 51-round bout in 1799, and won the rematch in the following year to become champion. He lost an eye in 1803 whilst playing fives, and evaded challenges to his title until 1805 when he lost - in eighteen rounds - to Hen Pearce.
In 1807 Belcher returned to the Prize Ring and lost to the outstanding new talent Tom Cribb in 31 rounds. Virtually ruined by the huge gambling losses he sustained at this fight he caused a fracas after the bout, for which he spent four weeks in prison. He died in London in 1811, a broken man.
During his career, Belcher was known as "The Napoleon of the Ring" and the "Black Diamond."