| O.S.S. | ITV | adventure television series | 1 | 26 |
| O.T.T. | — | — | — | — |
| Oakie Doke | British Broadcasting Corporation, CBeebies, CBC Television, Telemundo | — | 2 | 28 |
| Oasis | Amazon Prime Video | science fiction television series | 1 | 1 |
| Oasis | ITV | — | 1 | 10 |
| Obese: A Year to Save My Life | — | documentary film | 1 | 9 |
| Object Z | — | — | — | — |
| Oblivious | ITV | game show | 1 | — |
| Obsession: Dark Desires | ID | — | 3 | 21 |
| Obsessive Compulsive Cleaners | — | — | 5 | 35 |
| Occupation | BBC One | drama film | — | 3 |
| Ocean Wreck Investigation | — | documentary television program | — | — |
| Oceans | — | nature documentary | 1 | 8 |
| Odd Man Out | ITV | comedy television series | 1 | 7 |
| Odd One In | Rai 1 | — | 2 | 16 |
| Off the Bar | — | — | — | — |
| Off the Beaten Track | — | — | 1 | 6 |
| Off the Hook | BBC Three | sitcom, college life television program | 1 | 7 |
| Off Their Rockers | ITV1 | — | — | — |
| Off to Philadelphia in the Morning | — | — | — | — |
| Office Gossip | BBC One | sitcom | 1 | 6 |
| OFI Sunday | ITV | — | — | 6 |
| Oh Boy! | ITV | pop music | — | — |
| Oh Happy Band! | BBC One | sitcom | 1 | 6 |
| Oh No, It's Selwyn Froggitt! | ITV | sitcom | 4 | 29 |
| Oh, Brother! | BBC One | sitcom | 3 | 19 |
| Oh, Doctor Beeching! | BBC One | sitcom | 2 | 19 |
| Oh, Mr. Toad | ITV | — | 1 | 13 |
| Oil Strike North | — | — | 1 | 13 |
| OK! TV | Channel 5 | — | 1 | 208 |
| Old Bear Stories | ITV | — | 3 | 41 |
| Old Jack's Boat | CBeebies | — | — | — |
| Oliver Twist | BBC One | drama television series | — | 12 |
| Oliver Twist | — | drama television series | 1 | 4 |
| Oliver's Travels | — | drama television series | — | — |
| Olly the Little White Van | — | — | — | 65 |
| Omnibus | BBC One | documentary film | — | — |
| On Assignment | ITV | — | — | — |
| On Hannibal's Trail | — | documentary film | 1 | 6 |
| On Safari | ITV | children's television series | 1 | 7 |
| On Safari | ITV | children's television series, game show | 4 | 55 |
| On the Ball | — | — | — | — |
| On the Buses | ITV | sitcom | 7 | 74 |
| 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 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 |