| Year | Title | Role | Notes |
| 1996 | The Bill | Kelly Martin | Episode: "Unlucky in Love" |
| 1997–1998 | Coronation Street | Zoe Tattersall | 126 episodes |
| 1999 | Bad Girls | Rachel Hicks | 4 episodes |
| dinnerladies | Sigourney | Episode: "Catering" |
| 2000 | Nature Boy | Jenny Macalister | Miniseries, 3 episodes |
| Other People's Children | Becky | 2 episodes: "#1.2" and "#1.3" |
| Lorna Doone | Lizzie Ridd | Television film |
| 2001 | A Touch of Frost | Anne | 2 episodes: "Benefit of the Doubt", Parts 1 & 2 |
| Casualty | Lucy Curry | Episode: "Better Safe Than Sorry" |
| 2002 | Nice Guy Eddie | Mandy | Episode: "#1.2" |
| Paradise Heights | Julia Sawyer | 6 episodes |
| The Stretford Wives | Dawn Richards | Television film |
| 2003 | Danielle Cable: Eyewitness | Danielle Cable | Television filmNominated—Royal Television Society Award for Best Actress |
| Red Cap | Pte. Tracy Walters | Episode: "Crush" |
| The Last Detective | Celia / Josie | Episode: "Pilot" |
| 2004 | Island at War | Angelique Mahy | Miniseries, 6 episodes |
| 2006 | Missing | Sybil Foster | 2 episodes |
| Life on Mars | Ruth Tyler | 3 episodes |
| See No Evil: The Moors Murders | Maureen Smith | 2 episodes: "#1.1" and "#1.2" |
| The Street | Kerry | Episode: "Sean and Yvonne" |
| Rebus | Gail Maitland | Episode: "Strip Jack" |
| 2007 | Murder in the Outback | Joanne Lees | Television film |
| 2008 | Spooks: Code 9 | Hannah | Episodes: "#1.1" and "#1.2" |
| 2009 | Moving On | Kellie | Episode: "Butterfly Effect" |
| Robin Hood | Kate | 11 episodes |
| 2010 | Identity | Jane Calshaw | Episode: "Chelsea Girl" |
| The Royle Family | Saskia | Episode: "Joe's Crackers" |
| 2010–2015 | Downton Abbey | Anna Bates (née Smith) | 52 episodesGolden Globe Award for Best Supporting Actress (2014)Screen Actors Guild Award for Outstanding Performance by an Ensemble in a Drama Series (2012, 2014, 2015)Nominated—Primetime Emmy Award for Outstanding Supporting Actress in a Drama Series (2012, 2014, 2015)Nominated—Screen Actors Guild Award for Outstanding Performance by an Ensemble in a Drama Series (2013) |
| 2012 | True Love | Ruth | Episode: "Nick" |
| 2014 | The Secrets | Lexie | Episode: "The Lie" |
| Doc McStuffins | Florence Nightingale (voice) | Episode: "Let the Nightingale Sing" |
| 2015–2018 | Bob the Builder | Wendy (voice) | 112 episodes |
| 2016 | Dark Angel | Mary Ann Cotton | 2 episodes: "#1.1" and "#1.2" |
| 2017–2020 | Liar | Laura Nielson | Main role12 episodes |
| 2019 | The Commons | Eadie Boulay | Main roleMiniseries, 8 episodes |
| 2021 | Angela Black | Angela Black | Main role6 episodes |
| 2022 | Sherwood | Sarah Vincent | 3 episodes |
| 2023 | North Shore | Abigail Crawford | Main role6 episodes |
| Last Light | Elana Yeats | Main roleMiniseries, 5 episodes |
| 2024 | Breathtaking | Dr. Abbey Henderson | Main roleMiniseries, 3 episodes |
| 2025 | MobLand | Jan Da Souza | |
