After graduating the University of Miami, Larson moved to New York, where he was hired as an assistant for director Mike Nichols. He worked for Angels in America, Monty Python's Spamelot on Broadway, and Closer.
Larson eventually made an animated series that "morphed over time into Pennyroyal Academy," his book series. The movie rights were later given to actress and producer Reese Witherspoon and film producer Bruna Papandrea's company, Pacific Standard.
He is currently a writer for My Little Pony: Friendship is Magic.