New Zealand jockey James McDonald has been banned for 18 months and lost his riding contract with leading stable Godolphin.
The Australian-based 24-year-old pleaded guilty to making a bet last year that earned him $4000.
Stewards say there was no evidence to suggest McDonald had been party to any other bets.
James McDonald winning the Stella Artois Auckland Cup on Shez Sinsational. Photo: Photosport
McDonald tweeted that he had made a mistake betting, had broken the rules and accepted responsibility - but believed the penalty was too harsh and would appeal it.
Reports suggest suspension could cost McDonald up to $3 million in earnings.
McDonald was made Godolpin's top jockey in Australia last year.
The Godolphin Stable says there must be zero tolerance of any breach of betting regulations.