Sammy Mosberg began to box with the Pastime Athletic Club in 1912. During World War I he served as a boxing instructor and won his base championship. At the Olympic trials in 1920 Mosberg lost but was allowed to go to Belgium as an alternate. He defeated one of the men chosen above him and was selected to fight in Antwerp. He justified the decision by winning the gold medal, and en route, scored the one of the quickest knockouts in Olympic boxing history. Mosberg turned professional when he returned to the United States and fought for three years. He may have had as many 57 career fights without distinction, but they are not well-documented, as boxrec.com credits him with a career record of 8-7-2. After retiring from boxing he entered the family furniture business and later became a real estate broker. In 1953 he served as the coach for the U.S. Maccabiah Games boxing team. Mosberg was inducted into the International Jewish Sports Hall of Fame in 1985.