He did assistant animation to Ralph Bakshi films, The Lord of the Rings and American Pop.
He produced the Hanna-Barbera animated series SWAT Kats: The Radical Squadron.
His work also includes Scooby-Doo on Zombie Island, The Smurfs and several other Hanna-Barbera animated cartoons.
Doi has received three Emmy Award nominations, one in 1994 for The Town Santa Forgot and two in 1998 for Cow and Chicken and Dexter's Laboratory.
He was also nominated for a CableACE Award in 1996 for The Chicken from Outer Space, an animated short with the main characters from the eventual series Courage the Cowardly Dog.