| Year | Title | Role | Notes |
| 1971 | The Failing of Raymond | Girl patient | Credited as Catherine Louise Sagal |
| 1972 | The Bold Ones: The New Doctors | Young nurse | Credited as Katie Sagal |
| 1973 | Columbo | Secretary | Episode: "Candidate for Crime" (credited as Katie Sagal) |
| 1974 | Larry | Cashier | TV film |
| 1975 | The Dream Makers | Unemployment manager |
| 1985–1986 | Mary | Jo Tucker | 13 episodes |
| 1987–1997 | Married... with Children | Peggy Bundy | Main role |
| 1990 | Mother Goose Rock 'n' Rhyme | Mary Quite Contrary | TV movie |
| Tales from the Crypt | Ms. Kilbasser | Episode: "For Cryin' Out Loud" |
| The Earth Day Special | Peggy Bundy | |
| 1991 | She Says She's Innocent (Violation of Trust) | Susan Essex | TV movie |
| 1995 | Trail of Tears | Annie Cook |
| Nachtshow | | Episode: "February 10th, 1995" |
| Duckman | Ivana Duckman | Voice, episode: "The Germ Turns" |
| 1996 | Space Cases | Ma | Voice, episode: "Mother Knows Best" |
| 1997–2001 | Recess | Flo Spinelli | Voice, 3 episodes |
| 1998 | Rugrats | Additional voices | 1 episode[which?] |
| Chance of a Lifetime | Irene Dunbar | TV movie |
| Mr. Headmistress | Harriet Magnum |
| 1999 | No Higher Love | Ellen Young |
| Smart House | Pat |
| That '70s Show | Edna Hyde | 3 episodes |
| 1999–present | Futurama | Turanga Leela | Voice, main role |
| 2000 | Tucker | Claire Wennick | 13 episodes |
| 2001 | The Geena Davis Show | Ashley | Episode: "Girls' Night Out" |
| 2002 | Imagine That | Barb Thompson | 2 episodes |
| 2002–2005 | 8 Simple Rules for Dating My Teenage Daughter | Cate S. Hennessy | 76 episodes |
| 2004 | When Angels Come to Town | Jo | TV movie |
| 2004–2006 | Higglytown Heroes | Monica the Police Officer | 3 episodes |
| 2005 | Three Wise Guys | Shirley Crown | TV movie |
| Campus Confidential | Naomi Jacobs |
| Ghost Whisperer | Francie Lewis | Episode: "Undead Comic" |
| 2005–2007 | The Shield | Nancy Gilroy | 2 episodes |
| 2005–2010 | Lost | Helen Norwood | 4 episodes |
| 2006 | Boston Legal | Barbara Little | 5 episodes |
| The Search for the Funniest Mom in America | Host | Reality show |
| 2007 | The Winner | Lydia Berko | Episode: "Hot for Teacher" |
| 2008 | Eli Stone | Marci Klein | 2 episodes |
| CSI: Crime Scene Investigation | Annabelle Bundt/Natasha Steele | Episode: "Two and a Half Deaths" |
| 2008–2014 | Sons of Anarchy | Gemma Teller Morrow | 92 episodes |
| 2010 | Chadam | Sandy | Web series |
| 2013 | Glee | Nancy Abrams | Episode: "Wonder-ful" |
| 2014 | The Simpsons | Turanga Leela | Voice, episode: "Simpsorama" |
| 2014–2015 | Regular Show | Mordecai's Mom, Aunt Maxine | Voice, 2 episodes |
| A to Z | Narrator | Voice, 13 episodes |
| 2015 | The Bastard Executioner | Annora of the Alders | 10 episodes |
| 2016 | The Big Bang Theory | Susan | Episode: "The Conjugal Conjecture" |
| This Is Us | Lanie Schultz | Episode: "The Big Three" |
| 2016–2017 | Brooklyn Nine-Nine | Karen Peralta | 2 episodes |
