| Year | Title | Role | Channel | Notes |
| 1996 | French and Saunders | Various characters | BBC One | 4 episodes; with Sue PerkinsAlso credited for additional material |
| The Vicar of Dibley | Mary Tinker | 1 episode |
| 1997–98 | Light Lunch | Co-presenter | Channel 4 | With Sue Perkins |
| 1998–99 | Late Lunch |
| 1999 | Gimme Gimme Gimme | Beverly-Jane | BBC2 | Series 1 episode 5: "Saturday Night Diva" |
| 2005 | Blessed | Sue Chandler | BBC One | |
| 2006 | Mist: The Tale of a Sheepdog Puppy | Voice of Mist | Channel 5 | One-off TV film |
| Richard Hammond's 5 O'Clock Show | Co-presenter | ITV | 1 series; with Richard Hammond |
| 2008–11 | Sorry, I've Got No Head | Various characters | CBBC | |
| 2010 | Miranda | Life coach | BBC Two | 1 episode |
| 2010–16 | The Great British Bake Off | Co-presenter | BBC Two (2010–13)BBC One (2014–16) | 7 series; with Sue Perkins |
| 2011–14 | Sadie J | Ms. V | CBBC | |
| 2013, 2016, 2017,2022, 2023 | Have I Got News for You | Guest presenter | BBC One | 5 episodes |
| 2014 | Draw It! | Presenter | Channel 4 | 1 series |
| Collectaholics | BBC Two |
| Vertigo Road Trip | BBC One | One-off show |
| 2015–16 | Now You See It | Narrator | BBC One | 2 series |
| 2015 | The Gift | Co-presenter | BBC One | 1 series; with Matt Baker |
| Mel and Sue | ITV | 1 series; with Sue Perkins |
| Relatively Clever | Presenter | Sky1 | 1 series |
| Eurovision Song Contest 2015 | Co-commentator | BBC Three | Semi-finals; with Scott Mills |
| The Sound of Music Live | Frau Schmidt | ITV | One-off special |
| 2016–19 | Eurovision: You Decide | Presenter | BBC Four (2016)BBC Two (2017—19) | With Måns Zelmerlöw (2018–19) |
| 2016 | Eurovision Song Contest 2016 | Co-commentator | BBC Four | Semi-finals; with Scott Mills |
| Horrible Histories | Various | CBBC | 2 episodes |
| 2017 | Let It Shine | Co-presenter | BBC One | 1 series; with Graham Norton |
| The Secret Chef | Narrator | ITV | 1 series |
| Let's Sing and Dance for Comic Relief | Co-presenter | BBC One | 1 series; with Sue Perkins |
| Taskmaster | Herself | Dave | Series 4 |
| Eurovision Song Contest 2017 | Co-commentator | BBC Four | Semi-finals; with Scott Mills |
| Pitch Battle | Presenter | BBC One | 1 series |
| Mary, Mel and Sue's Big Christmas Thank You | One-off special | 1 series |
| 2017– | Letterbox | Presenter | BBC Two | 2 series |
| Children in Need | Co-presenter | BBC One | with Graham Norton and Ade Adepitan |
| 2018 | The Generation Game | Co-presenter | BBC One | 1 series; with Sue Perkins |
| Eurovision Song Contest 2018 | UK spokesperson | BBC One, EBU | |
| 2020– | Hitmen | Co-Star | Sky1 | 2 series; with Sue Perkins |
| 2021–24 | Mel Giedroyc: Unforgivable | Presenter | Dave | 3 series |
| 2021 | Strictly Come Dancing Christmas Special | Contestant | BBC One | With professional dance partner Neil Jones |
| 2021–22 | One Night In... | Narrator | Channel 4 | 4 episodes |
| Handmade: Britain's Best Woodworker | Presenter | Channel 4 | 2 series; (2021) (2022) |
| 2022 | The Really Really Rude Puppet Show (w/t) | Host | Channel 4 | 6 episodes |
| 2023 | Eurovision Song Contest 2023 | Co-commentator | BBC One | Final; with Graham Norton |
| Mary Makes It Easy | Guest | BBC Two | With host Mary Berry |
| 2024 | 90 Day Fiancé UK Tell All | Host | Discovery+ | |
| 2024– | Pictionary | Host | ITV1 | Quiz show |
| 2025 | The Masked Singer | Teeth | Contestant: Series 6 |
| Win Win | Co-host | Game show; with Sue Perkins |
| 2026 | LOL: Last One Laughing UK | Contestant | Amazon Prime Video | Series 2 |
