McCartney was born on April 9, 1987, in Ardsley, Westchester, New York, the son of Ginger (Sarber) and Scott McCartney.[1][2] He began performing in local community musicals at the age of seven, before joining the national tour of The King and I at age ten along with Phil of the Future star Ricky Ullman. There he played the character of Louis. In 1998, he sang with the group Sugar Beats and can be heard on their 1998, 1999, and 2000 CD releases.