Irish sailor Peter O'Leary has been let off with a warning after betting on a direct competitor to win at the 2008 Beijing Games.
O'Leary placed two bets worth a total of $600 on the British boat to capture the gold medal in the Star class at odds of 12-1, and won $7,200.
The IOC says there was no proof of any match-fixing, and the athlete was unaware he could not bet on Olympic events.
The IOC bars athletes from betting on Olympic events but the organisation's ethics commission said competitors in 2008 may not have been as familiar with the regulations as they are now.
O'Leary failed to qualify for the medal race on which he had bet.
The affair, which broke just before he competed at the London Games earlier this year, made headlines and prompted an IOC investigation.