At age of twelve, Mahon and her older sisters played for a local basketball team sponsored by the Brandon Cotton Mill, where their father worked as a truck driver.

Part of a modest and big family, Mahon decided to take a job in a cotton mill while completing her senior year in high school.

While it was common practice for men's mill teams to put talented ball players on the local payroll to shore up the strength of their lineup, the girls just played for fun.

She finished college in 1942 with a degree in physical education, and spent one year in Whitmire, South Carolina, teaching all subjects to a class of seventh graders.

In the same year, a talent scout offered Mahon and Thompson an invitation to come to the newly founded All-American Girls Professional Baseball League tryouts, which were to be held at Wrigley Field in Chicago, Illinois.

Mahon responded with a hitting streak which spanned 13 games, tying an all-time record set by Rockford Peaches' Mildred Warwick in 1943.

Along the way, she was chosen for the AAGPBL All Star team on two occasions (1946, 1949), and posted a career batting average of .248 (721-for-2903), including 432 runs and 400 RBI in 837 game appearances.

Her 400 RBI ties her with Pepper Paire for fourth best in the AAGPBL's all-time list, behind Dorothy Schroeder (431), Inez Voyce (422) and Eleanor Callow (407).

Mahon is one of only two South Carolina natives to play in the All-American Girls Professional Baseball League, the other being her longtime friend Viola Thompson, who had been inducted in the SCAHOF in 1998.