Hillenberg began his career as a marine biology teacher at the educational organization formerly known as the Orange County Marine Institute. It was there that his interest in aquatic life and animation combined. As a teaching tool, he would write and illustrate stories.
In 1987, he left his job to become an animator. “Changing careers like that is scary" he said
. "But the irony is that animation is a pretty healthy career right now and science education is more of a struggle."
After pursuing degrees in Experimental Animation at the California Institute of Arts in Valencia and earning his Master of Fine Arts in 1992, he was hired by Nickelodeon based on the success of award-winning animated short Wormholes (1992). From 1993 to 1996, he worked on Rocko’s Modern Life as a director and writer.
He then began work on what would eventually become SpongeBob SquarePants, the first episode of which aired in May of 1999. The juggernaut is still the network’s most popular “Nicktoon,” with nearly 250 episodes airing over a run that is still in progress.