| | | | | | |
| | Drivers highlighted like this have won a final during the current season | |
| |  indicates this driver has been interviewed  indicates that pictures are needed for this driver | |
| | Gareth O Beirne, Morcambe | | 412 : 2011 to 2014 | | |
| | Harry O Brian, London | | 216 : 1959 | | |
| | Chris O Brien, Coventry | | 432 : 1992 | | |
| | John O Brien, Alderley Edge | | 486 : 1981 to 1989, 87 : 2001, 86 : 2020 to 2024 | | |
| | Paul O Brien, Leeds | | 363 : 1985 to 1986 | | |
| | Shaun O Brien, Burnley | | 86 : 1981 to 1985 | | |
| | J. O Connell | | S20 : 1956 | | |
| | Billy-Tom O Connor | | 318 : 2006 to 2007, 316 : 2015 to 2017 | | |
| | Glen O Connor | | 194 : 2021 | | |
| | Johnny "Burn Em Up" O Connor, Feltham | | F1 : 1954, 12A : 1955, 12A : 1958 | | |
| | Kerry O Connor, Netherlands | | H82 : 1997 | | |
| | Frank O Dell, Corby | | 182 : 1957 | | |
| | Mick O Hara, Mansfield | | 305 : 1959, 372 : 1962 to 1972 | | |
| | Malcolm O Hare, Liverpool | | 500 : 1958 | | |
| | Paul O Neil, British Touring Car Driver (BTCC) | | 259i : 2022 to 2024 | | |
| | John O Neill, Wimslow | | 486 : 1980 | | |
| | Ken "Knock-out" O Neill, Salford | | B147 : 1954, 21 : 1955 to 1956, 4 : 1958 to 1964 | | |
| | Paul O Shea, Bromley | | 127 : 1956 to 1957 | | |
| | Phil O Shea, Romford | | 27i : 1954, 27A : 1955 | | |
| | John O Sullivan, Swindon | | 572 : 2022 | | |
| | Pat O Sullivan, Ware | | 240 : 1973 to 1974 | | |
| | Vic O Toole, Pelsall | | 371 : 1954, 24i : 1955 | | |
| | Callum Oakes-Kitson, March | | 533 : 2018 to 2020, 533 : 2022 | | |
| | Charlie Oates, Liverpool | | 202 : 1954 to 1955 | | |
| | Howard Oatway, Manchester | | 298 : 1981 | | |
| | Tich Ockwell, Blunsdon | | 53 : 1954 | | |
| | Ted Oddy | | 104A : 1954 | | |
| | Len Ogbourne, Northampton | | 76 : 1954, 57A : 1955, 76 : 1957 to 1958, 51 : 1960 to 1961 | | |
| | Phil Ogle, New Zealand | | NZ282 : 2013, NZ282 : 2016 | | |
| | Peter Oldfield, Sheffield | | 217 : 1979 | | |
| | Bill Oldstead | | 259A : 1954 | | |
| | Dennis Oliver, Ilford | | 365 : 1955, 77 : 1956 to 1957 | | |
| | Michael Oliver, Aberystwyth | | 357 : 2012 to 2013 | | |
| | Jack Ollerenshaw, Grindleton | | 87 : 1962, 26 : 1963 to 1984 | | |
| | Malcolm Olley, Aylesbury | | 287 : 1963 to 1966 | | |
| | Tim Olley, Winslow | | 487 : 1991 to 1993 | | |
| | Andrew Olorenshaw, St.Leonards on Sea | | 273 : 2016 to 2017 | | |
| | Colin Onions, Melton Mowbray | | 255 : 1983 to 1984 | | |
| | John Onions, Loughborough | | 141 : 1980 | | |
| | Jos Op-tRoodt, Belgium | | B67 : 2007 to 2010 | | |
| | Graham Ord, Gatley | | 306 : 1959 to 1960 | | |
| | Michael Orr, Bedworth | | 185 : 1975 to 1977 | | |
| | Fred Orrell, Nottingham | | 487 : 1982 | | |
| | Mark Orwin, Hertford | | 409 : 1989 | | |
| | Fred Osborn, Plymouth | | P13 : 1954 to 1955 | | |
| | Lloyd Osborne, Huddersfield | | 94 : 1974 to 1975 | | |
| | Gary Osbourne, Leamington Spa | | 255 : 1982 | | |
| | Kevin Osbourne | | 241 : 2011 to 2012 | | |
| | Mark Osbourne, Pointon | | 529 : 2017 | | |
| | Roy Osbourne, Weedon | | 356 : 1983 | | |
| | Vic Osbourne, London | | 99 : 1962 | | |
| | Auke Osinga, Netherlands | | H592 : 2019, H592 : 2023 | | |
| | Sam Ostle, Kirkby Stevens | | 351 : 1969 to 1983 | | |
| | Paul Oswald, Newcastle-upon-Tyne | | 174 : 1966 | | |
| | Martijn Oudhuis, Netherlands | | H477 : 2009 to 2012, H477 : 2014 to 2016, H477 : 2018 to 2019 | | |
| | Tijn Oudhuis, Netherlands | | H477 : 2024 to 2025 | | |
| | Jack Overy, Soham | | 61 : 2015 to 2017 | | |
| | Paul Owen, Houghton Regis | | 254 : 1994 | | |
| | Mike Owers, Chelmsford | | 119 : 1971 | | |
| | Raymond Oxberry, Fallowfield | | 180 : 1958 | | |
| | Arthur Oxland, Stratford | | 82 : 1954, 72i : 1955, 72 : 1957 to 1959 | | |
| | Graham Oxley, Heanor | | 63 : 1974 | | |
| | Michael Oxley, Heanor | | 64 : 1974 | | |
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