|Representing the United States|
|Pan American Games|
|1975 Mexico City||Team dressage|
|1975 Mexico City||Individual dressage|
Winnett competed as a member of the United States Equestrian Dressage team in the 1972 Olympics in Munich, Germany and as a reserve rider in the 1976 Olympics held in Montreal, Canada. In 1980 Winnett qualified for the U.S. Olympic team but did not compete due to the Olympic Committee's boycott of the 1980 Summer Olympics in Moscow, Russia. He was one of 461 athletes to receive a Congressional Gold Medal instead.
- Evans, Hilary; Gjerde, Arild; Heijmans, Jeroen; Mallon, Bill; et al. "John Winnett". Olympics at Sports-Reference.com. Sports Reference LLC. Archived from the original on April 18, 2020. Retrieved April 11, 2013.
- Caroccioli, Tom; Caroccioli, Jerry. Boycott: Stolen Dreams of the 1980 Moscow Olympic Games. Highland Park, IL: New Chapter Press. pp. 243–253. ISBN 978-0942257403.
- John Winnett at Olympedia