Born in Toronto, Ontario, McCarthy's mother was born in Saint Vincent and the Grenadines while her father was born in Jamaica. She grew up in Ajax playing basketball, volleyball, track, soccer and golf with her and her fathers' personal coach Karim Corringham.[2]
On January 11, 2013, as part of the NWSL Player Allocation, McCarthy joined the Western New York Flash.[4] Despite this, McCarthy only played 15 minutes for the Flash and her allocation was not picked up for the following year.[5]
In 2006, McCarthy was 14 years old when she made her debut in the Canadian youth program. She won a bronze medal at the 2008 CONCACAF Women's Under-17 Championship and represented Canada at the FIFA U-17 Women's World Cup in New Zealand the same year.[2]