In 2001, Catlett was nominated for an Annie Award for her voice-over work as Mrs. Puff, placing in the category "Best Voice Acting by a Female Performer in an Animated Production."Tom Kenny (voice of the title character) was also nominated in the same year, making Catlett and Kenny the first two SpongeBob cast members to be nominated for an award. As of 2019, being a voice actor on SpongeBob SquarePants is her only regular television role. Catlett described herself as "basically retired" in 2013, since she is good friends with the other SpongeBob cast members, making the SpongeBob recording booth an easy environment that requires less preparation than in-person performances.
For the first seven seasons, Mary Jo Catlett exclusively voiced Mrs. Puff. Staring in season 8, she has voiced some other characters, such as Grandma Tentacles and some background fish.
Her previous acting roles in other productions have been referenced on the show; for example, SpongeBob says, "Hello, Dolly!" in "Something Smells," nodding to the 1964 Broadway musical that introduced the phrase and starred Mary Jo Catlett as a main cast member.
In 2009, Mary Jo Catlett starred in the film Surprise Surprise, and she was constantly asked to do her Mrs. Puff voice. According to her costars, "not one person on the movie let a day go by without calling some relative ... and handing their cell phones to Mary Jo to do her best 'Oh no, SpongeBob, no!'"
She attended the 2013 SpongeBob Fan Shellabration where she signed autographs and posed for pictures with a mascot costume of Mrs. Puff.