| Red Beard Art Ltd | Administrative & support | 2016 |
| Red Day Properties Limited | Real estate | 2019 |
| Red DOT Tours Limited | Administrative & support | 2000 |
| Red Kite Housing Ltd | Real estate | 2026 |
| Red Kite Leasing Limited | Wholesale & retail | 2018 |
| Red Kite Spray Foam Removal Ltd | Construction | 2025 |
| Red Knife Limited | Professional & scientific | 2019 |
| Red Lion Cassington Ltd | Hospitality | 2025 |
| Red Sector Recruitment Ltd | Administrative & support | 2017 |
| Red Tarn Holding Ltd | Financial services | 2026 |
| RED27MOBILE Limited | Wholesale & retail | 2017 |
| Redbeard IT Limited | Information & communication | 2018 |
| Redbrick Corporate Limited | Administrative & support | 2011 |
| Redfin Consulting Ltd | Professional & scientific | 2015 |
| Redkeyit Limited | Information & communication | 2017 |
| Redline Rapid Response Ltd | Health & social care | 2025 |
| Redthorne Residents Management Company Limited | Households | 2009 |
| Refinovate Limited | Professional & scientific | 2021 |
| Reflections Property Group Ltd | Real estate | 2017 |
| Reflex LAB Limited | Information & communication | 2012 |
| Refundo Limited | Financial services | 2025 |
| Refurb Commercial Developments Ltd | Construction | 2021 |
| Regent Park Group Ltd | Other services | 2019 |
| Rehoboth Coaching Ltd | Health & social care | 2020 |
| REJ Investments Limited | Financial services | 2018 |
| Relate Then Educate Psychology Limited | Education | 2022 |
| Release Life Sciences and Diagnostics Ltd | Professional & scientific | 2018 |
| Relics of Witney Limited | Wholesale & retail | 2001 |
| Remo Dental Laboratory Limited | Information & communication | 2019 |
| Renaissance Beauty Ltd | Extraterritorial | 2008 |
| Renard Pubs Ltd | Hospitality | 2023 |
| Renese Ltd | Financial services | 2026 |
| Renewables Servicing Company Ltd | Manufacturing | 2025 |
| Rentacure Limited | Construction | 1981 |
| Reonox Ltd | Information & communication | 2024 |
| Repeat the Pattern Limited | Professional & scientific | 2020 |
| Resilient Landscapes Yorkshire CIC | Professional & scientific | 2023 |
| Resonate Mentoring CIC | Education | 2026 |
| Responsible Sourcing Solutions Limited | Professional & scientific | 2025 |
| Responsible Wealth Ltd | Financial services | 2013 |
| Restore Home Limited | Wholesale & retail | 2021 |
| Retreats by Mulberry Ltd | Administrative & support | 2025 |
| Retreats Linen Ltd | Other services | 2026 |
| Retyped Ltd | Information & communication | 2024 |
| Revival Design and Build Ltd | Construction | 2025 |
| Revive Productions Ltd | Arts & recreation | 2018 |
| Revive Skin & Spa Ltd | Other services | 2018 |
| Revotek Ltd | Administrative & support | 2023 |
| RF Europe Limited | Financial services | 2005 |
| RGT Solutions Limited | Professional & scientific | 2012 |
| RH Utility Insights Limited | Construction | 2025 |
| Richard Ward (Oxford) Holdings Limited | Professional & scientific | 2019 |
| Richard Ward (Oxford) Limited | Construction | 1984 |
| Richards Interiors and Estates Ltd | Extraterritorial | 2022 |
| Ridgemarch Limited | Construction | 2010 |
| Ridgeway Farriers Limited | Other services | 2018 |
| Ridgeway Homes of Oxford Ltd | Construction | 2015 |
| Riemann Limited | Health & social care | 2016 |
| Right Interiors Limited | Real estate | 1985 |
| Riide Ltd | Information & communication | 2015 |
| Rimac Energy R&D UK Limited | Professional & scientific | 2021 |
| Rincha Ltd | Hospitality | 2024 |
| RISE4 Ltd | Construction | 2024 |
| Rising Kites Limited | Professional & scientific | 2023 |
| Risk for Rewards Limited | Arts & recreation | 2024 |
| Rita Clifton Limited | Professional & scientific | 2012 |
| Riverside Analytics Ltd | Professional & scientific | 2014 |
| Riverwood Plumbing Limited | Construction | 2025 |
| RJC Landscaping Limited | Administrative & support | 2017 |
| RJP & SON Limited | Construction | 2012 |
| RJR Contracting Limited | Agriculture & fishing | 2017 |
| RJR Custom Drums Ltd | Wholesale & retail | 2016 |
| RKH Skyline UK Limited | Real estate | 2020 |
| RLT Mechanical Services Ltd | Wholesale & retail | 2017 |
| RM OPS Strategy Limited | Professional & scientific | 2022 |
| RMA Assets Limited | Real estate | 2005 |
| RN Bespoke Joinery & Cabinetry Ltd | Construction | 2018 |
| Roadlok UK Ltd | Wholesale & retail | 2020 |
| ROB Waller Limited | Wholesale & retail | 2011 |
| Robert Harter Limited | Professional & scientific | 2013 |
| Rock Advanced Mobility Limited | Manufacturing | 2023 |
| Rock Engineering Limited | Manufacturing | 2021 |
| Rocket Clothing Company Limited | Manufacturing | 1997 |
| Rockwall Systems Ltd | Construction | 2025 |
| Rocome Electrical Contractors Limited | Construction | 2012 |
| Rocome Renewable Energy Limited | Construction | 2017 |
| Rocomm Limited | Real estate | 1992 |
| Roetel Limited | Hospitality | 2011 |
| Roger Bradley Fitness Limited | Arts & recreation | 2002 |
| Rogers Advisory Limited | Professional & scientific | 2022 |
| Rogers Wharf Farm Limited | Real estate | 2023 |
| Rogerson Southward Ltd | Real estate | 2024 |
| ROK Energy Solutions Ltd | Manufacturing | 2026 |
| Rolbac Limited | Information & communication | 2012 |
| Rolldark Ltd | Arts & recreation | 2020 |
| Roo's Kitchen Ltd | Hospitality | 2023 |
| Roost and Perch Ltd | Real estate | 2018 |
| Roost Online Limited | Professional & scientific | 2009 |
| Root & Wild Ltd | Administrative & support | 2025 |
| Root Ideas Limited | Information & communication | 2010 |