Mohardt attended the University of Notre Dame from 1918 through 1921 where he played football under Knute Rockne and also competed in baseball and track and field.

He was selected as an All-American halfback in 1921 but lost his last year of collegiate eligibility for participating in a professional football game against the Green Bay Packers in December 1921.

He served as a lieutenant colonel in the U.S. Army Medical Corps during World War II in the North African and Italian Campaigns.

"[8] Mohardt was selected as a first-team member of 1921 College Football All-America Team by Lawrence Perry and a second-team All-American by Walter Camp.

[11][12] He was subsequently charged with, and eventually admitted, playing for the Racine Legion team on December 4, 1921, in a professional game against the Green Bay Packers.

[13] Mohardt also reportedly played semi-pro baseball in Iowa while attending Notre Dame during the summer of 1920, compiling a .309 batting average.

He left major league baseball with perfect 1.000 batting average and fielding percentage and two runs scored in his only two plate appearances.

[1] With the Tigers having Ty Cobb, Harry Heilmann and Bobby Veach in the outfield, Mohardt was unlikely to get significant playing time.

Accordingly, after a short stay in Detroit, manager Ty Cobb decided to send Mohardt to the minor leagues for seasoning.

The Detroit Free Press noted: "Although Mohardt gives promise of developing into a great player, he isn't ready for regular assignment in the major leagues.

On October 17, 1926, the Bulls played against the New York Yankees, an NFL team featuring Mohardt's former teammate, Red Grange.

[29] Mohardt subsequently opened a private medical practice on Michigan Avenue in Chicago and became known as one of the leading brain specialists in the Midwest.

[27] In January 1942, at age 43, and after the attack on Pearl Harbor, Mohardt closed his medical office on Michigan Avenue in Chicago and enlisted in the United States Army.

While waiting to be called to active duty, Mohardt told a reporter he felt "just like he did when he sat on the bench and the late Knute Rockne sent him into his first college game.

[31] In November 1961, at age 63, Mohardt committed suicide at his home in La Jolla by severing the femoral artery in his groin.