Kenny has voiced many other characters, including Heffer Wolfe in Rocko's Modern Life, the Ice King in Adventure Time and its spinoff Fionna and Cake, the Narrator and Mayor in The Powerpuff Girls, Carl Chryniszzswics in Johnny Bravo, Dog in CatDog, Starscream in Transformers: Animated, Hank and Jeremy in Talking Tom and Friends, The Penguin in various animated media based on DC Comics, and Spyro from the Spyro video game series.

[4] In their mid-teens, they saw an ad for an open-mic night at Skaneateles that featured comedian Barry Crimmins with the moniker "Bear Cat".

He appears in the live-action segments of SpongeBob SquarePants as Patchy the Pirate, appeared on R. L. Stine's The Haunting Hour: The Series on the season four episode, "Uncle Howee" as Uncle Howee, a high-energy kids' show host with strange powers.

"[11] He described SpongeBob's voice as in between that of a child and an adult, stating "Think a Stan Laurel, Jerry Lewis kind of child-man.

"[12] Joe Murray auditioned Kenny for voice acting roles for Rocko's Modern Life in a casting call in Los Angeles, California.

He voices many characters in The Powerpuff Girls, including the Mayor, the Narrator, Mitch Mitchelson, Snake and Little Arturo from the Gangreen Gang, Rainbow the Clown, etc.

Kenny also voiced several characters on the animated show Xiaolin Showdown, as well as the Autobots Skids and Wheelie in the live-action Transformers film series.

He played Mr. Hal Gibson in the animated kids show Super Robot Monkey Team Hyper Force GO!.

Kenan Thompson, Kristin Chenoweth, Jason Bateman, Nick Kroll, Cheri Oteri, Henry Winkler, Will Arnett, and Will Forte are the other main cast members.

[23] Kenny was a guest star on HarmonQuest as both himself and his "in-game character" Legnahcra the maître d' of Virtuous Harmony.

Kenny reprised his role as Ice King in the 2023 spinoff series Adventure Time: Fionna and Cake.

After the cancellation of Rocko's Modern Life in 1996, Hillenburg began developing his own concept for an ocean-themed series, building off of his background in marine science.

[28] The airing was recognized as honoring the show's creator Stephen Hillenburg, who had died one year earlier.

[29] Later in 2019, he was featured in the live recording of the Broadway musical SpongeBob SquarePants playing the role of Patchy the Pirate.

As part of a plan to maximize the use of its broadcasting rights partnership with the National Football League (NFL), Paramount decided to air an "alternative" Super Bowl telecast on Nickelodeon that was aimed to be more family-friendly.

[32] The broadcast on Nickelodeon was hosted by Nate Burleson and Noah Eagle in live-action and accompanying them were Spongebob and Patrick.

Kenny commented that the Nickelodeon airing allowed viewers who weren't football fans to still engage with the game.