John Winnett was born in Los Angeles but spent much of his youth in Europe where he began riding dressage and jumping. He was 1945 French Junior National Champion in dressage. Moving back to the United States Winnett worked as a stockbroker, but retired in 1970 to devote himself to equestrian sport and training dressage horses. He and his wife settled in Wellington, Florida where they taught dressage and jumping and trained horses. Winnett competed at the 1975 Pan American Games, winning a silver medal in individual dressage and a gold in team dressage. Winnett wrote the book Dressage as Art in Competition, first published in 1993.