After college, Leahy got a job at the sports radio station WEEI in Boston. After a two-year stint at WEEI, she transitioned to a position as an official reporter of the Boston Celtics and Celtics.com. She turned that into a job at FOX Boston, where she covered all Boston area sports teams.[7][8]
Leahy moved to Los Angeles in 2012 and covered a variety of different sports, most notably as a sideline reporter for Turner Sports' March Madness coverage. She worked for a variety of CBS affiliated sports outlets, including the local CBS Los Angeles news. Leahy then became the sideline reporter for American Ninja Warrior on NBC.[9] In September 2015, she took a job to join former ESPN Radio host Colin Cowherd on his new show after his exodus to FOX. Cowherd cited a lack of female voices in sports talk radio as a reason for Leahy's addition to the show, as well as Leahy's history of developing useful sources as a sports journalist.[10]
On May 17, 2017, Leahy had a heated exchange with LaVar Ball on The Herd with Colin Cowherd.[11] Ball never faced in Leahy's direction for the whole interview, apparently trying to talk only with Colin Cowherd on the other side of the studio.[12] When Leahy asked Ball how many shoes he had already sold, he said "stay in your lane" and called her a "hater", which led to accusations of sexism against Ball.[11][13]