He became the British 125 cc. champion aged just 20, and finished second in the world championships for that class a year later. A spectacular crash in Daytona in 1975 threatened to end his career, breaking his left thigh, right arm, collarbone and two ribs, yet he recovered and was racing again shortly afterwards.
In 1976 he won five grands prix, bringing him the world title, a feat he repeated the following year.
In 1979, he moved from the Suzuki works team, believing that he was receiving inferior equipment to his teammates. He shifted to a privateer Yamaha machine, but soon started receiving works equipment. A 1982 crash largely ended Sheene as a title threat, and he retired in 1984.
Sheene was a colourful, exuberant character who used his good looks, grin, and Cockney accent to good effect in self-promotion, and combined with an interest in business was one of the first riders to make large amounts of money from riding.
He moved to Australia in the late 1980s in the hope of relieving some of the pain of injury-induced arthritis, moving to a property near the Gold Coast. He combined a property development business with a role as a commentator on motor sport, first at the Nine Network with the famously loud Darrell Eastlake, then moving with the TV coverage of the motorcycle grands prix to Channel Ten. Sheene's commentary style was idiosyncratic, to say the least. Never letting the audience wonder for a minute exactly what he thought of a rider, bike, or team, his biases were completely transparent. He combined insight into the skills of riding, and the vagaries of the professional circuit, with a penchant for the occasional double entendre delivered with a trademark grin.
In latter years, Sheene became involved in historic motorcycle racing, usually thrashing the awed amateurs behind him.