In 2012, he co-starred in the film White Frog. That same year, Posey voiced a character in the pilot of the Disney original cartoon SheZow, which aired on May 4 as a part of the Shorty McShorts' Shorts miniseries. The two regularly auditioned for the same roles as child actors. He auditioned for the role of Jacob Black in the Twilight film series in 2007 but lost the role to his friend Taylor Lautner. In February 2002, he appeared in the film Collateral Damage in December of that year, he played the main character's son in the romantic comedy Maid in Manhattan. Posey has worked steadily in film and television.
He is of Mexican descent on his mother's side. Posey was born in Santa Monica, California, to Cyndi Terese Garcia and actor-writer John Posey.