A native of Aurora, Illinois, John Mauer lost both parents by the age of 13 and was raised by a sister. With the support of a local businessman, Mauer attended the University of Illinois, where his roommate was Harold "Red" Grange.

During his tenure at the University of Illinois, Mauer participated in athletics; in his senior year, he was named Outstanding Athlete and Scholar in the Big Ten Conference.

He was also one of the first college basketball players to use the "one hand" shot.

Following graduation from college, Mauer began a long and distinguished career in coaching. He got his first big opportunity when he was offered the University of Kentucky basketball coaching position in 1927. He preceded Adolph Rupp and compiled a record of 40 wins and 14 losses during his three years coaching the Wildcats.

In the early 1930's, Coach Mauer moved to Miami of Ohio where he coached with Paul Brown and Webs Eubank. Also while at Miami, he coached one of his favorite players, Walter "Smoky" Alston, who went on to fame with the Brooklyn and Los Angeles Dodgers.

With that move, he became the first and only man to be head coach in the same sport at three different SEC schools.