| O.C.Colston Limited | Agriculture & fishing | 1957 |
| Oatpoint Limited | Construction | 1965 |
| Ofec Consulting Limited | Information & communication | 2005 |
| Over Norton Park Limited | Agriculture & fishing | 1963 |
| Oxforce Limited | Health & social care | 2007 |
| Oxford Business Management Limited | Professional & scientific | 2005 |
| Oxford Community Gardeners Ltd | Administrative & support | 2023 |
| Oxford Ergonomics Limited | Health & social care | 2007 |
| Oxford Health Care Limited | Professional & scientific | 1989 |
| Oxfordshire Glass Ltd | Construction | 2011 |
| Oxlingua Ltd | Education | 2017 |
| Oxola Limited | Information & communication | 2016 |
| P M Cole Joinery Ltd | Construction | 2004 |
| P.R. Alcock & Sons Limited | Construction | 2025 |
| P.R. Alcock Holdings Limited | Financial services | 2025 |
| P.R. Alcock Properties Limited | Construction | 1952 |
| Pagelime Limited | Professional & scientific | 1993 |
| Pappy's Takeaway Ltd | Hospitality | 2023 |
| Parr Court Residents Association (Banbury) Limited | Real estate | 1979 |
| Partridge Electrical Ltd | Construction | 2005 |
| PAT Thomas (Butchers) Limited | Wholesale & retail | 1986 |
| Paul Clarkson Electrical Ltd | Construction | 2009 |
| Paul Webber Racing Limited | Administrative & support | 2002 |
| PB Windows & Doors Limited | Construction | 2007 |
| PBG Projects Limited | Construction | 2012 |
| Pelle London Limited | Wholesale & retail | 2016 |
| Pentalith Property Company Limited | | 1978 |
| Peroshi Limited | Information & communication | 2014 |
| Peter Goss Butchers Ltd | Wholesale & retail | 2008 |
| Pettits of Wallingford Limited | Wholesale & retail | 1962 |
| Pettitt & Cunningham | | 1994 |
| Pharaon Events Limited | Arts & recreation | 2008 |
| Pharaos Ltd | Real estate | 2006 |
| Pinkneys Green (06) Limited | Real estate | 2006 |
| Poots Brothers Limited | Real estate | 2023 |
| Practical Learning (UK) Limited | Education | 2000 |
| Prestige Cars (Banbury) Limited | Transport & logistics | 2005 |
| Print Concern Ltd | Manufacturing | 1992 |
| Proofpoints Customer Advocacy Limited | Information & communication | 2026 |
| PRP Polymer Engineering Limited | Manufacturing | 1987 |
| Public Affairs Associates Limited | Administrative & support | 1980 |
| Purely Air Tech Ltd | Construction | 2016 |
| Quickstride Ltd | Information & communication | 2007 |
| R.J.Johnson & Co. Limited | Professional & scientific | 1916 |
| R.N.Willmer(Farms)Limited | Agriculture & fishing | 1950 |
| R.Oakey & Sons,Limited | Transport & logistics | 1948 |
| Radcot Agricultural Products Limited | Extraterritorial | 1979 |
| Raine Mouldings Limited | Manufacturing | 1989 |
| Ravenscroft Building Limited | Construction | 2014 |
| Red Kite Property Limited | Construction | 2004 |
| Reesrussell LLP | | 2006 |
| RER Limited | Professional & scientific | 2002 |
| Restranaut Limited | Information & communication | 1987 |
| Rgbm Electrical Limited | Wholesale & retail | 1992 |
| Rial Consultancy Limited | | 1992 |
| Richard Holmes Property Consultants Limited | Financial services | 2008 |
| Robert Crosby Plumbing Services Limited | Construction | 2007 |
| Rogers Metal Management LLP | | 2018 |
| Rolly Toys Limited | | 1978 |
| RPB Consulting (UK) Ltd | Professional & scientific | 2013 |
| Ruby Cornerstone LLP | | 2023 |
| Rupert Gooddy Plants Limited | Agriculture & fishing | 1987 |
| S K S (Oxford) Limited | Wholesale & retail | 2004 |
| S Morgan & Sons Limited | Agriculture & fishing | 2018 |
| S.J.Farrant & SON Limited | Agriculture & fishing | 1952 |
| Safemove Property Management Limited | Real estate | 1989 |
| Scope Space Mission Limited | Professional & scientific | 2003 |
| Sheridan Associates Limited | Real estate | 1975 |
| Smith's Haulage (Bletchington) Limited | Transport & logistics | 1979 |
| Smithley Ltd | Professional & scientific | 2025 |
| SO Storage Limited | Real estate | 2014 |
| Sofi DE France Ltd | Hospitality | 2007 |
| Solution 7 Limited | Information & communication | 1997 |
| South Oxfordshire Scaffolding Co. Limited | | 1980 |
| Spectronex Ltd. | Professional & scientific | 2005 |
| SPS Swimming Pool Services Ltd | Construction | 2001 |
| SSI Property Holdings Limited | Administrative & support | 2016 |
| ST. Hugh's School (Carswell) Trust Limited | Education | 1967 |
| Streamline Office Services Limited | Other services | 1975 |
| Strict Baptist Mission(The) | Health & social care | 1907 |
| Sumgreat Limited | | 1985 |
| Summerton Mill Limited | Information & communication | 2004 |
| Susurro Limited | Wholesale & retail | 2021 |
| Swain Electrical Limited | Construction | 2006 |
| Swan Foundry (Banbury) Limited | Manufacturing | 1947 |
| Swift Inc. Ltd | Arts & recreation | 2005 |
| Swift UK Home Improvements Ltd | Other services | 2016 |
| Syntagm Limited | Information & communication | 1985 |
| Synth-Isis Ltd | Professional & scientific | 2004 |
| System Supply Industries Limited | Information & communication | 2013 |
| T. & K. Brown and Sons Limited | Agriculture & fishing | 1972 |
| Tarrant Anderson Touring Services Ltd | Arts & recreation | 2019 |
| Taylor and Taylor Care Limited | Health & social care | 2020 |
| Tech XB Limited | Professional & scientific | 2005 |
| Ternaville Contractors & Plant Limited | | 1982 |
| Ternaville Engineers Limited | | 1974 |
| Thai Orchid Restaurant Limited | Hospitality | 1998 |
| Thame Glass Windows Holdings Limited | Professional & scientific | 2006 |
| Thames Valley Boiler Care Ltd | Construction | 2007 |
| Thames Valley Property Management Ltd | Real estate | 2012 |