| On the House | — | — | — | — |
| On the Move | — | — | — | — |
| On the Record | — | — | — | — |
| On the Rocks | — | — | — | — |
| On the Spot | BBC One | game show | 1 | 6 |
| On the Up | — | sitcom | 3 | 19 |
| On the Waterfront | British Broadcasting Corporation | — | — | — |
| On the Yorkshire Buses | Channel 5 | — | 1 | 8 |
| On Thin Ice | — | documentary film | — | — |
| Once Upon a Time in Iraq | — | — | — | — |
| Once Upon a Time in Londongrad | — | — | — | — |
| Once Upon a Time in Northern Ireland | BBC Two | — | — | — |
| One Born Every Minute | SBS6 | documentary television program | 9 | 67 |
| One by One | British Broadcasting Corporation | drama television series | 3 | 32 |
| One Child | Sundance TV | — | 1 | 3 |
| One Foot in the Grave | BBC One | sitcom | 6 | 44 |
| One Foot in the Past | — | documentary film | — | — |
| One Hundred and Eighty | — | game show | 1 | 8 |
| One Man and His Dog | BBC Two | — | — | — |
| One Man and His Hob | — | — | — | 13 |
| One Night | BBC One | — | 1 | 4 |
| One Night Only | ITV1 | — | — | 7 |
| One Pair of Eyes | — | — | — | — |
| One Summer | — | — | — | 5 |
| Only an Excuse? | BBC One | sitcom | — | 20 |
| Only Child | — | — | — | — |
| Only Fools and Horses | BBC One | sitcom | 7 | 64 |
| Only Human | Channel 4 | documentary film, documentary television program | — | — |
| Only in America | — | — | 1 | 10 |
| Only When I Laugh | ITV | sitcom | 4 | 29 |
| OOglies | — | comedy television series | 3 | 46 |
| Ooh La La! | — | — | — | — |
| Oops TV | — | — | 2 | 107 |
| Open Air | BBC One | — | 4 | — |
| Open All Hours | BBC Two | sitcom | 4 | 26 |
| Open Door | BBC Two | — | — | — |
| Open House | — | — | — | — |
| Open House with Gloria Hunniford | Channel 5 | — | 6 | 135 |
| Open Space | BBC Two | — | — | — |
| Open to Question | BBC Scotland | current affairs | — | — |
| Opening Shot | — | — | — | — |
| Operation Good Guys | BBC Two | comedy television series | 3 | 19 |
| Operation Grand Canyon with Dan Snow | BBC Two | — | 1 | 2 |
| Operation Ouch! | BBC Children's and Education | — | 6 | 55 |
| Opinions | — | — | — | — |
| Orange Playlist | — | — | — | — |
| Orange unsignedAct | Channel 4 | — | — | — |
| Oranges Are Not the Only Fruit | BBC Two | LGBT-related television series | — | 3 |
| Orangutan Diary | — | nature documentary | — | 11 |
| Orangutan Jungle School | — | — | 3 | — |
| Orbit: Earth's Extraordinary Journey | BBC Two | documentary film | 1 | 3 |
| Orchestra United | — | — | — | — |
| Ordeal by Innocence | BBC One | thriller television series, drama television series | — | 3 |
| Order to View | — | — | — | — |
| Ordinary Lies | — | — | 2 | 6 |
| Origins of Us | — | documentary film | — | — |
| Orlando | ITV | thriller television series | 4 | 76 |
| Orm and Cheep | ITV | children's television series | — | 26 |
| Orson Welles' Great Mysteries | ITV | anthology series | 1 | 26 |
| Orson Welles' Sketch Book | — | — | 1 | 6 |