Career
She competed for Ireland at the 2012 Summer Olympics, finishing 26th overall in the 100 metre breaststroke and 22nd overall in the 200 metre individual medley, where she came third in her heat. In 2013 McMahon took up a scholarship to study at Texas Agricultural and Mechanical University. In her Freshman year she became the second-fastest Agricultural and Mechanical Aggie ever in the 100 metre breaststroke when she finished fourth in the event at the Securities and Exchange Commission Championships with a time of 59.35 seconds.