Maruyama has appeared on television in supporting roles in a number of sitcoms, including recurring characters on The Jamie Foxx Show, Strip Mall, Suddenly Susan, and Arrested Development. Maruyama is well known as an improv performer and instructor, and was a featured guest on the American and British versions of Whose Line Is It Anyway?, as well as being a member of The Groundlings. She also appeared as a parking lot attendant in an episode of Curb Your Enthusiasm.
She played a nurse in The Bucket List (2007) and a housekeeper in the 2012 film The Campaign. She is part of the cast of The Jim Henson Company's live stage show "Puppet Up! - Uncensored" which has toured to Aspen, Las Vegas, Edinburgh, Sydney and Melbourne and is currently appearing monthly at Avalon Hollywood.
Maruyama was also featured as a fashion victim in an episode of the makeover show How Do I Look?. She also appeared as a non-celebrity contestant on the 1984 CBS game show, Body Language, under the name Karen Upshaw, saying she was from Perris, California. She was paired with celebrity players Ted Lange and Constance Towers. She was also on The New $25,000 Pyramid in 1983 with Audrey Landers and Michael McKean.
|1990||Circuitry Man||Biker Bandit|
|1992||Doogie Howser, M.D.||Kathy Walker||Episode "Do the Right Thing... If You Can Figure Out What It Is"|
|1994||Viper||Police Operator||Episode "Pilot"|
|1994||Pulp Fiction||Gawker #1|
|1994||Ellen||Kate||Episode "Adam's Birthday"|
|1995||The Enforcer||Voice Only|
|1995||Murphy Brown||Wardrobe Woman||Episode "It's Miller Time"|
|1995||The American President||Leo's Assistant|
|1996||Dunston Checks In||Telephone Operator|
|1996||Mad About You||Nurse #2||Episode "The Procedure"|
|1996||Rudy Coby: Ridiculously Dangerous||Grandma||TV Movie|
|1996||Captain Simian & the Space Monkeys||Shao Lin||Voice Only, episodes "Invasion of the Banana Snatchers" and "Splitzy's Choice"|
|1997||Night Stand||Miyoshi||Episode "Leave Your Job or I'm Leaving You"|
|1997||Caroline in the City||Actress||Episode "Caroline and the Wayward Husband"|
|1997||Blade Runner||Fish Dealer||Video game, voice only|
|1998||Veronica's Closet||Event Official||Episode "Veronica's Got a Secret"|
|1998||Holding the Baby||Mona||Episode "Father Knows Breast"|
|1998||Guys Like Us||Kim||Recurring character|
|1998||Suddenly Susan||Mrs. Fong||5 episodes|
|1999||The Thirteenth Year||Mrs. Nelson||TV Movie|
|1997–1999||The Simpsons||Japanese Stewardess, Dancing Lady #1||Voice only, episodes "Thirty Minutes Over Tokyo" and "In Marge We Trust"|
|2000||The Wild Thornberrys||Leopard||Voice only, episode "Black and White and Mom All Over"|
|2000||King of the Hill||Buddhist||Voice only, episode "Won't you Pimai Neighbor?"|
|2000||Titus||Nurse Patty||Episode "Episode Eleven"|
|2000||Static Shock||Kim||Voice only, episode "Grounded"|
|2000||Curb Your Enthusiasm||Female Parking Attendant (Joanna)||Episode "Interior Decorator"|
|1999 – 2001||The Jamie Foxx Show||Gloria||11 episodes|
|2001||Futurama||Amazonian||Voice only, episode "Amazonian Women in the Mood"|
|2001||Even Stevens||Millie||Episode "A Weak First Week"|
|2001||Strip Mall||Foo||9 Episodes|
|2001||Heavy Gear: The Animated Series||Yoji Kirakowa||Voice only|
|2002||Justice League||Tsukuri, Firefighter||Voice only, episodes "Fury" and "Fury: Part II"|
|2003||Columbo||Maid||Episode "Columbo Likes the Nightlife"|
|2003||Spider-Man: The New Animated Series||Head Protestor, Shadowy Woman, Flower Vendor||Voice only, episodes "Heroes and Villains" and "Royal Scam"|
|2005||The King of Queens||Connie||Episode "Black List"|
|2007||The Bucket List||Nurse Shing|
|2012||The Campaign||Mrs. Yao|
|2013||Good Luck Charlie||Coach||Episode "Go Teddy!"|
|2013||2 Broke Girls||Su-Min Lee||Episode "And the Girlfriend Experience"|
|2014||Garfunkel & Oates||Susie||Episode: "Rule 34"|
|2016||Go-Go Boy Interrupted||Liz||Episode: "My First Time Doing Porn"|
|2018||Heathers||Mrs. Finn||3 episodes|
|2018||Life of the Party||Mediator|
- "Interview "The Campaign" Actress Karen Maruyama". AsianInNY. Blog.AsianInNY.com. Archived from the original on August 10, 2012. Retrieved August 21, 2018.
- "Karen Maruyama". TheGroundlings.com. The Groundlings Theatre & School. Retrieved August 21, 2018.
- "How Do I Look?". CBS Interactive Inc. Retrieved August 21, 2018.