Mahoney attended Sturgis Brown High School in Sturgis, South Dakota. As a senior, she was named Gatorade and United States of America Today South Dakota Player of the Year, High School Girls Athlete of the Year by the South Dakota Sports Writers Association, and Mission Basketball South Dakota. Mahoney also excelled academically, earning membership in the National Honor Society.
Mahoney attended Kansas State University and was a 2003 All Big-12 First Team selection.
During her career, she set the all-time school record for assists (589), and she ranks second all-time in assist-to-turnover ratio (162).