Lieb was a two-time National Collegiate Athletics Association (NCAA) national collegiate champion in the discus in 1922 and 1923, and the Amateur Athletic Union (AAU) national open champion in 1923 and 1924. He is widely credited with introducing the modern spin delivery that is still used today. At the 1924 Summer Olympics held in Paris, France, Lieb competed for the United States in the discus throw and won the bronze medal, but did not equal the distance of his qualifying throw. Several weeks after the Olympics ended, Lieb broke the discus world record with a throw of 47.61 meters (156 feet 2½ inches).
Lieb's coaching success was recognized when he was offered the head coaching position at Loyola University in Los Angeles, California, where he remained from 1930 to 1938. Lieb relished his role as the Loyola Lions head football coach, posing with lion cubs in publicity photographs, and posted an overall record of 47–33–4. Lieb also started Loyola's ice hockey program as an off-season conditioning program for his football players, but quickly built the team into a powerhouse with an annual rivalry with the University of Southern California. From 1935 to 1938, Lieb's hockey Lions won four consecutive Pacific Coast Intercollegiate League titles and compiled a 38–3–2 record. Lieb quit his coaching job at Loyola during his wife's illness in 1939, and then decided to leave California after she died.
In 1940, Lieb succeeded Josh Cody as the head football coach at the University of Florida in Gainesville, Florida, with high expectations based on his prior successes with Notre Dame and Loyola. He also served as Florida's athletic director. Lieb, however, was unable to duplicate the same level of success with the Gators that he had at Notre Dame and Loyola. In his five seasons of coaching the Florida Gators football team from 1940 to 1945, Lieb compiled a 20–26–1 record, and his contract was not renewed after the 1945 season. Thereafter, Lieb worked as the assistant Crimson Tide football coach and head track & field coach at the University of Alabama, where his old Notre Dame teammate Frank Thomas was the head football coach, from 1946 to 1951.
When Lieb retired in 1951, he returned to Los Angeles, where he became a public speaker. He died of an apparent heart attack in 1962 at age 62. He was elected to the Loyola Marymount Hall of Fame posthumously in 1987.