Allen was born at Cherry Point, North Carolina to Mary Jo (Allen) and Joseph Marsh. He attended Concordia University in Saint Paul, Minnesota before serving with the 548th Reconnaissance Technical Group at Hickam Air Force Base, Hawaii and later at the Joint Intelligence Center Pacific at Pearl Harbor. While living in the college town of Springfield, Missouri he became a part of its robust film and theatre community and eventually relocated to Los Angeles. Allen appears as screenwriter Alvin Sargent in the Paramount+ series The Offer (2022) opposite Josh Zuckerman and Colin Hanks. He plays producer Lou Adler in season two of the HBO series Winning Time: The Rise of the Lakers Dynasty (2022), with Jason Segel and Adrien Brody, and the title character in Johnny Malibu (2023).