In 1988, he finished second aboard Play The King in the Breeders' Cup Sprint.
Following their 1989 Triple Crown with the colt With Approval, in 1990 they repeated the feat with Izvestia, an achievement that has never been equalled.
Don Seymour retired in 1994 having won the Sovereign Award as Canada's top jockey a record four times.
In 1995 he was voted the Avelino Gomez Memorial Award in recognition of his significant contribution to the sport of horse racing.
He died on 26 June 2020, at the age of 58, from complications of chronic obstructive pulmonary disease (COPD).