Her father is the special teams coordinator for the Las Vegas Raiders in the National Football League (NFL).
She helped lead UCLA to the 2022 national championship, playing every minute of their comeback from 2–0 down against North Carolina to win 3–2 in the title game.
[1][4] In her senior season, with the program's move to the Big Ten Conference, she matched her sophomore total of 3 goals and a team-high 6 assists.
During her years at UCLA, head coach Margueritte Aozasa mostly used McMahon at left back but occasionally put her on the right or up forward when needed.
[1][5] San Diego Wave FC announced on December 13, 2024, that they had signed McMahon to a three-year contract.