From February 1994[1] to December 2009, he was the president of 4Kids Productions, a former subsidiary of 4Kids Entertainment and Leisure Concepts.
He produced five seasons of the new Teenage Mutant Ninja Turtles, five Pokémon movies, and one Yu-Gi-Oh!
Grossfeld also developed and co-wrote the successful stage adaptation of the Pokémon series, which premiered at Radio City Music Hall and toured the United States and Canada in late 2000 to early 2001.
[2] Grossfeld broke new ground in reality television with NBC's InSport, a show that set the stage for sports magazine series now on the air.
Grossfeld has also produced, written and/or directed a variety of television programs, including Lifestyles of the Rich and Famous hosted by Robin Leach.