| Mark Mann Limited | Professional & scientific | 2021 |
| Match Poker Services Limited | Arts & recreation | 2018 |
| MAX and Mojo Limited | Professional & scientific | 2013 |
| MAX and Mojo Sports Management Limited | Wholesale & retail | 2025 |
| MAX Steventon Ltd | Health & social care | 2025 |
| Medicinechest Limited | Administrative & support | 2000 |
| Mellow Yellow Limited | Other services | 2005 |
| Mercuso Ltd | Other services | 2026 |
| Metruely Ltd | Education | 2026 |
| MFR Holdings Limited | Financial services | 2025 |
| Miana Ltd | Wholesale & retail | 2019 |
| Mida Interiors Limited | Professional & scientific | 2018 |
| Middleton Farriery Ltd | Manufacturing | 2023 |
| Midland Felt Roofing Limited | Construction | 1964 |
| Midsummer Nightcap Limited | Wholesale & retail | 2016 |
| MK Catering Group Ltd | Hospitality | 2025 |
| Momo Oxford Ltd | Hospitality | 2025 |
| Moonpaw Studios Ltd | Professional & scientific | 2025 |
| Mount Athos Pilgrimages Ltd | Administrative & support | 2025 |
| MP Build Solutions Ltd | Construction | 2024 |
| MP Fleet Services Ltd | Extraterritorial | 2025 |
| Multiple Finance Limited | Financial services | 2001 |
| Mustard Property Investments Limited | Real estate | 2017 |
| Mustard Sheep Limited | Agriculture & fishing | 2017 |
| Mwls Enterprise Ltd | Hospitality | 2024 |
| Narwhal Innovation Ltd | Professional & scientific | 2021 |
| Neil Clarke Architecture Limited | Professional & scientific | 2014 |
| Nimi and ME Limited | Administrative & support | 2022 |
| Noragi Limited | Wholesale & retail | 2024 |
| Northern Monkey Consulting Ltd | Professional & scientific | 2012 |
| Northlodge Holdings Ltd | Real estate | 2018 |
| Northmoor Estates 2 Limited | Construction | 2016 |
| Novus Finitorium Ltd | Education | 2018 |
| Number 14 Woodstock Ltd | Real estate | 2021 |
| Nuovo Consultancy Ltd | Professional & scientific | 2026 |
| O'Neil Hair Limited | Other services | 2002 |
| Oldbrook Music Ltd | Information & communication | 2020 |
| Oliver Scott Curry Research Limited | Professional & scientific | 2020 |
| One Estimating Ltd | Professional & scientific | 2020 |
| Oota Strategic Consulting Ltd | Professional & scientific | 2025 |
| Orbit RRI Limited | Information & communication | 2020 |
| OUR Cube CIC | Education | 2023 |
| OUR Future INT Limited | Administrative & support | 2022 |
| OX & Bean Limited | Hospitality | 2025 |
| Oxford Asphalt Co. Limited (the) | Construction | 1974 |
| Oxford Bankside Brewing Limited | Manufacturing | 2019 |
| Oxford Bowen Limited | Other services | 2013 |
| Oxford Campus Buttery Limited | Hospitality | 2010 |
| Oxford Chinese Education Centre Ltd | Education | 2023 |
| Oxford Dynamics Consulting Limited | Information & communication | 2020 |
| Oxford Finance Limited | Real estate | 1986 |
| Oxford Kitchens Ltd. | Wholesale & retail | 1991 |
| Oxford Systems Engineering Ltd | Professional & scientific | 2025 |
| Oxford Technica Ltd | Professional & scientific | 2011 |
| Oxfordmeta Group Ltd | Professional & scientific | 2020 |
| Oxfordshire Digital Ltd | Information & communication | 2013 |
| Oxhealth Consulting Ltd | Information & communication | 2023 |
| Oxprox Limited | Information & communication | 2021 |
| Oxvalue.Ai Limited | Professional & scientific | 2021 |
| P & a Brickwork Limited | Construction | 2019 |
| P.S. Ponting Developments Ltd | Construction | 2006 |
| P.S. Ponting Limited | Wholesale & retail | 1983 |
| Palaeopi Limited | Information & communication | 2018 |
| Park Town Property Ltd | Real estate | 2018 |
| Park View Childcare (Woodstock) Ltd | Health & social care | 2024 |
| Park View Woodstock Management Company Limited | Real estate | 2019 |
| Paul KAY Hair Salon Ltd | Other services | 2026 |
| Pavenham Limited | Financial services | 2011 |
| PB Storage Solutions Ltd | Transport & logistics | 2024 |
| Perdiswell Limited | Agriculture & fishing | 2012 |
| PGM Planning and Developments Limited | Professional & scientific | 2018 |
| Phoenix V Limited | Information & communication | 2024 |
| Picnic at the Palace Ltd | Wholesale & retail | 2021 |
| Pivotal Thread Ltd | Professional & scientific | 2026 |
| Plunkett Foundation | Professional & scientific | 1926 |
| Ponting Residential Limited | Real estate | 2016 |
| Preferred by Nature UK Limited | Professional & scientific | 2009 |
| Prestige VIP Chauffeurs Limited | Transport & logistics | 2021 |
| Prize Brand Limited | Professional & scientific | 2004 |
| Project Active Ltd | Arts & recreation | 2011 |
| PYE Homes Limited | Construction | 2006 |
| Pygmalion Interiors Limited | Other services | 1998 |
| QT and Co UK Ltd | Hospitality | 2026 |
| Quadway Developments Limited | Real estate | 2016 |
| R.A.G. Properties Limited | Real estate | 2003 |
| R.C.P. Properties Ltd | Construction | 2001 |
| Rapid Business Performance Ltd | Professional & scientific | 2022 |
| Reduce Limited | Professional & scientific | 2019 |
| Resilient Risk and Health Solutions Limited | Financial services | 2023 |
| Rhubarb Rhubarb of Stow Ltd | Wholesale & retail | 2024 |
| Rick's Autos Limited | Wholesale & retail | 2019 |
| Rick's Cycles Limited | Other services | 2019 |
| Ridge and Partners LLP | | 2004 |
| Ridge Surveyors Limited | Administrative & support | 1995 |
| Rightsize Data Solutions Ltd | Water & waste | 2025 |
| RIO Delta Limited | Wholesale & retail | 2021 |
| Rise Bidco Limited | Administrative & support | 2023 |
| Rise Holdco Limited | Administrative & support | 2023 |
| Rise Midco Limited | Administrative & support | 2023 |
| Rise Newco 1 Limited | Administrative & support | 2023 |