| O'Brien | — | talk show | 1 | 10 |
| 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 Giants | BBC One | nature documentary | 1 | 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 |
| Office Monkey | ITV2 | — | 2 | — |
| OFI Sunday | ITV | — | — | 6 |
| Oh Boy! | ITV | pop music | — | — |
| Oh Happy Band! | BBC One | sitcom | 1 | 6 |
| Oh In Colour | — | comedy television program | — | 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 |
| Oktober | — | — | — | — |
| 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 Twist | — | — | — | — |
| Oliver's Travels | — | drama television series | — | — |
| Oliver's Twist | Food Network | cooking show | — | 52 |
| Olly the Little White Van | — | — | — | 65 |
| Olobob Top | CBeebies | — | 1 | 52 |
| 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 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 |
| Oscar | — | — | 1 | 3 |
| Oscar Charlie | — | children's television series | — | — |
| Other People's Children | BBC One | drama television series | 1 | 4 |
| Our Crime | — | documentary film | — | — |
| Our Friends in the North | BBC Two | drama television series | — | 9 |
| Our Girl | BBC One | drama television series | 4 | 28 |
| Our House | ITV1 | sitcom | 2 | 39 |
| Our Man at St. Mark's | — | — | — | — |
| Our Man in... | Channel 4 | documentary television program | 1 | 3 |
| Our Miss Pemberton | — | — | — | — |
| Our Mutual Friend | BBC Two | — | — | 4 |
| Our Mutual Friend | BBC One | — | 1 | 12 |
| Our Mutual Friend | British Broadcasting Corporation | — | 1 | 7 |
| Our Oceans | — | — | — | — |
| Our Planet | Netflix | documentary film | 2 | 12 |
| Our School | — | — | — | — |
| Our World War | BBC Three | docudrama | 1 | 3 |
| Our Zoo | BBC One | drama | 1 | 6 |
| Out Of Bounds | BBC One | drama television series | 1 | 6 |
| Out of Her Mind | BBC Two | — | — | — |
| Out of Hours | — | — | — | — |
| Out of Sight | ITV | comedy television series, children's television series | 3 | 27 |
| Out of Step | — | — | — | — |
| Out of the Blue | — | crime television series | 2 | 12 |
| Out of the Unknown | BBC Two | science fiction television series, fantasy television series, anthology series | 4 | 49 |
| Out of This World | ABC Television Limited | science fiction television series, anthology series | 1 | 13 |
| Out of Tune | BBC Children's and Education | comedy television series | 3 | 40 |
| Outlander | Starz | fantasy television series, drama television series, adventure television series, historical television series, romance television series | 8 | 101 |
| Outlander: Blood of My Blood | Starz | historical drama, romantic drama, time travel, fantasy television series, drama television series, romance television series | 2 | 12 |
| Outlaws | BBC Three | — | 1 | 12 |
| Outnumbered | BBC One | sitcom | 5 | 35 |
| Outrageous | — | drama | — | 6 |
| Outrageous Acts of Science | — | — | 7 | 87 |
| Outside Edge | — | — | — | — |
| Outside Man | — | documentary television program | — | — |
| Outsiders | — | — | — | — |
| Outtake TV | BBC One | comedy television series | — | — |
| OutTHERE | — | — | — | — |
| Over to William | — | — | — | — |
| Overseas Press Club - Exclusive! | — | — | — | 13 |
| Owen, M.D. | — | — | 2 | 61 |
| Oxbridge Blues | BBC Two | — | — | 7 |
| Oxford Road Show | BBC Two | — | 5 | 63 |
| Oz and Hugh Raise the Bar | — | documentary film | 1 | 4 |
| Oz and James Drink to Britain | BBC Two | documentary film | 1 | 8 |