Baer was born in Nebraska in 1909 with four siblings. He became Heavyweight Champion of the World in 1934, a title he held for one year.

He was accused of committing sport-related injuries that led to the death of two opponent boxers, Frankie Campbell and Ernie Schaaf.

He also fought (and lost) to James J. Braddock, the storyline for the movie "Cinderella Man."

Baer was married twice and had three children. He died of chest pains, possibly from a heart attack, in California.