Bull attended the University of Pennsylvania, from which he graduated with a degree in dentistry. He played football for the Penn Quakers and was named to the All-American team in 1895. During a game between Penn and the Carlisle Indian Industrial School, Bull faced off against All-American and early professional footballer Bemus Pierce. Bull and Pierce faced each other on the line throughout the game, and on a play late in the game Pierce knocked Bull to the ground, and the play went over him. After the play, Pierce, who was a Native American, cried out to the Penn players, "Look, look at Sitting Bull." Bull also rowed for the Penn crew.