| RCB Project Solutions Limited | Information & communication | 2022 |
| RCG Business Consultancy Limited | Professional & scientific | 2013 |
| RCR Mistry Consulting Limited | Professional & scientific | 2023 |
| RD Creative Limited | Arts & recreation | 2023 |
| Rdelliott Limited | Professional & scientific | 2025 |
| RDW Consultant Limited | Administrative & support | 2022 |
| Re-Evolved Digital Limited | Administrative & support | 2015 |
| Re-Volt Limited | Professional & scientific | 2022 |
| Re:Store MCR Ltd | Wholesale & retail | 2023 |
| REA Ventures Limited | Professional & scientific | 2016 |
| Reach First AID Training Ltd | Education | 2022 |
| Ready Software Solutions Limited | Information & communication | 2023 |
| Reagens (UK) Limited | Administrative & support | 1996 |
| Real Building Solutions Limited | Professional & scientific | 2021 |
| Real Estate Equity (Investments) Limited | Administrative & support | 2010 |
| Real Financial Limited | Financial services | 2019 |
| Real Mortgage Services Limited | Financial services | 2019 |
| Really Clean Ltd | Administrative & support | 2025 |
| Realm Finance Limited | Professional & scientific | 2016 |
| Realm Legal Limited | Professional & scientific | 2015 |
| Realm Recruit Limited | Administrative & support | 2015 |
| Realm Resource Limited | Professional & scientific | 2016 |
| Rebel Marketing Limited | Professional & scientific | 2025 |
| Reboot Therapy Limited | Health & social care | 2017 |
| Rebourne Healthcare Ltd | Real estate | 2014 |
| REC Build Ltd | Construction | 2025 |
| Recarton UK Limited | Water & waste | 2012 |
| Recgenie Ltd | Information & communication | 2020 |
| Reciprocal Consulting Limited | Administrative & support | 2021 |
| Reclaimed World Limited | Wholesale & retail | 2013 |
| Recoilconsult Limited | Professional & scientific | 2024 |
| Recordworks Limited | Professional & scientific | 2025 |
| Recsuite Ltd | Administrative & support | 2024 |
| Recursion London Ltd | Professional & scientific | 2020 |
| Red Bird Management Limited | Professional & scientific | 2023 |
| Red Bridge Analytics Limited | Professional & scientific | 2025 |
| Red Circle Digital Ltd | Information & communication | 2013 |
| Red Coast Industries (UK) Limited | Financial services | 2023 |
| Red Edge Ltd | Construction | 2016 |
| Red Lantern Catering Ltd | Hospitality | 2019 |
| Red Ledger Ltd | Professional & scientific | 2022 |
| Red Mountain Consulting Limited | Professional & scientific | 2024 |
| Red Noise Media Ltd | Information & communication | 2011 |
| Red Rock Data Limited | Information & communication | 2026 |
| Red Star Asset Management Ltd | Real estate | 2024 |
| Red Terracotta Properties Ltd | Real estate | 2024 |
| Red Wolf Rentals Limited | Real estate | 2025 |
| RED6 Digital Learning Limited | Professional & scientific | 2025 |
| Redberry Labs Ltd | Information & communication | 2025 |
| Redbridge Bury (Holdings) Limited | Professional & scientific | 2016 |
| Redchurch London Ltd | Information & communication | 2022 |
| Reddington Global Company Limited | Other services | 2021 |
| Redditch Medical Group Limited | Administrative & support | 1997 |
| Redditch Medical Limited | Manufacturing | 2021 |
| Rede House Ltd | Households | 2013 |
| Redesign Homes Ltd | Real estate | 2025 |
| Redfern Architectural Services Limited | Administrative & support | 2008 |
| Redford Holdings Limited | Financial services | 2021 |
| Redford Logistics & Recycling Serv's Ltd | Water & waste | 2012 |
| Redhill Real Estate Limited | Real estate | 2024 |
| Redical Limited | Real estate | 2023 |
| Redlands Interior Solutions Limited | Construction | 2018 |
| Redlink Consulting Limited | Professional & scientific | 2014 |
| Redman Roberts Limited | Wholesale & retail | 2004 |
| Redmark Products Limited | Manufacturing | 1986 |
| Redmen Projects Limited | Professional & scientific | 2022 |
| Redmouse Limited | Administrative & support | 2025 |
| Redpope Ltd | Extraterritorial | 2014 |
| Redsift Limited | Information & communication | 2014 |
| Redspot Contractors Limited | Construction | 1965 |
| Redw Properties Limited | Real estate | 2025 |
| Reebok International Limited | Financial services | 1983 |
| Reed Commercial Legal Services Limited | Professional & scientific | 2022 |
| Reed Solutions Limited | Professional & scientific | 2010 |
| Reengaged Ltd | Education | 2024 |
| Reeves Johnson Limited | Administrative & support | 2008 |
| Refine Sports Therapy Clinic Ltd | Health & social care | 2024 |
| Refined & Regal Limited | Wholesale & retail | 2024 |
| Reflect Clinic Limited | Health & social care | 2014 |
| Reflection AI UK Ltd. | Information & communication | 2025 |
| Refocusing Ltd | Wholesale & retail | 2026 |
| Reform and Flow Ltd | Arts & recreation | 2024 |
| Reform Coaching Limited | Other services | 2022 |
| Reform Legal Limited | Administrative & support | 2011 |
| Reform MCR Limited | Arts & recreation | 2024 |
| Reframe Change Ltd | Information & communication | 2026 |
| Reframe Psychology Limited | Professional & scientific | 2022 |
| Refrigerant Products Holdings Limited | Professional & scientific | 2012 |
| Refrigerant Solutions Limited | Manufacturing | 2004 |
| REG Excellence Ltd | Professional & scientific | 2023 |
| Regal Lettings and Property Management Kent Limited | Professional & scientific | 2010 |
| Regency Court Residents Company Limited | Households | 2000 |
| Regency Dental & Healthcare Ltd | Health & social care | 2019 |
| Regency Park Management Company Limited | Real estate | 1992 |
| Regenesis Events CIC | Professional & scientific | 2023 |
| Regent Fishbar Limited | Hospitality | 2006 |
| Regent Holder Limited | Hospitality | 2018 |
| Regent Road Nominees Limited | Professional & scientific | 1995 |
| Regents Gate Properties Ltd | Administrative & support | 2023 |
| Regina Caeli Consulting Limited | Professional & scientific | 2023 |