At the Paris Games, competing for Yugoslavia, he used his high score on the horizontal bar to win the gold medal in the all-around event by edging Robert Pražak of Czechoslovakia by .017 points. Štukelj earned a second gold medal in the horizontal bar contest and placed fourth in the long horse vault, the rings and the team events.
In 1928, he added to his medal haul with bronze medals in the all-around and team events, while taking another gold, this time on the rings. He also tied for seventh on the parallel bars. Štukelj skipped the 1932 Olympic Games in Los Angeles, but he returned in 1936 and, at the age of 37, he won a silver medal on the rings, to bring his career Olympic medal total to six.
In 1992, when he was 93 years old, Štukelj attended the Opening Ceremony of the Olympic Games in Barcelona and watched as athletes from Slovenia marched behind their own flag for the first time. Four years later, he was honoured at the Atlanta Opening Ceremony and amazed the crowd by bounding onto the stage at the age of 97. He died four days before his 101st birthday.