The 2005 St. James's Palace Stakes was a prestigious horse race held at Royal Ascot in England. It is a Group 1 flat race specifically for three-year-old thoroughbred colts and fillies. The event took place on June 14, 2005, and is part of the annual Ascot Racecourse meeting, which attracts top horses from around the world. In the 2005 edition, the race was won by the horse George Washington, trained by Aidan O'Brien. This victory added to the horse's impressive record and highlighted the significance of the St. James's Palace Stakes in the racing calendar, showcasing the best young talent in the sport.