Traveling as a youth with a show booth in which he played the violin and gave boxing exhibitions, Mace attracted the attention of a showman and former boxer. He began to fight in earnest in the early 1850s. Throughout his life he combined innkeeping and circus performing with fighting. Mace weighed only 160 pounds (73 kg), but he overcame his lack of bulk with speed and an effective left jab. He was the model of scientific boxing in England, as James J. Corbett later was in the United States. Mace won the English middleweight championship in 1860. He then won the English heavyweight title in 1861 and lost it the next year but once more was recognized as champion when his conqueror, Tom King, refused to fight him again.

Boxing as an international sport was advanced by Mace's visit to North America in 1870–71. On May 10, 1870, at Kennerville, La., he defeated Tom Allen in 10 rounds in a match advertised as the world championship. Mace is thus regarded as the last world heavyweight champion under London Prize Ring Rules. He retired late in 1871, but on Feb. 7, 1890, at almost 59, he lost to the world heavyweight contender Charley Mitchell in three rounds in an attempt to regain the English title. At a time when most prizefighters were considered highly dubious persons, Mace was universally respected for his integrity.