Drymon was born in Morristown, a small town in far northern New Jersey in 1968. He attended Jefferson Township and Dover Public Schools as a child, and supposedly he enjoyed drawing and making comic books. Drymon graduated from Jefferson Township High School in 1987. He attended the School of Visual Arts in New York to become an illustrator. After college, he was recruited by Disney feature animation for their internship program. Upon finishing the program he returned to New Jersey and then on to California.
Drymon was discovered by Nickelodeon in 1993. He moved to California to work as an animator for Nickelodeon. In 1993, Drymon also began working as a storyboard artist and writer for Rocko's Modern Life. It was here he met two of his future employers, Tim Hill and Stephen Hillenburg; Hill was a writer, Hillenburg a co-producer and storyboard artist. In 1997, Hillenburg created SpongeBob SquarePants. Drymon performed many duties on SpongeBob, including being a writer on all episodes, then supervising director and producer, and eventually creative director. Drymon also worked on the Cartoon Network animated series Camp Lazlo. Drymon worked on Tim Hill's side project, the popular KaBlam! skit Action League Now!, as a storyboard artist. He also wrote the Emmy Award-nominated episode of CatDog "Doggone".