| Reef Electrical Limited | Construction | 2005 |
| Reehome Limited | Real estate | 2021 |
| Reehome Property Limited | Real estate | 2022 |
| Reel Consulting Limited | Wholesale & retail | 2008 |
| Reel Occupational Health Limited | Health & social care | 2025 |
| Reelace Electrical Solutions Ltd | Energy | 2016 |
| Reelex Limited | Manufacturing | 2001 |
| Reeltime Apps Limited | Information & communication | 2019 |
| Reene's Ltd | Hospitality | 2022 |
| Reengage Learning Ltd | Education | 2026 |
| Reeseashley Ltd | Construction | 2025 |
| Reevabee Ltd | Administrative & support | 2025 |
| Reeve Solutions Ltd | Information & communication | 2026 |
| Reeves Consulting Limited | Professional & scientific | 2025 |
| Reeves Innovate Ltd | Information & communication | 2024 |
| Refaced Aesthetics Ltd | Other services | 2025 |
| Refan UK Ltd | Wholesale & retail | 2014 |
| Referee KIT & Equipment Retail Ltd | Wholesale & retail | 2023 |
| Reference Point Autos Ltd | Wholesale & retail | 2026 |
| Refergen Ltd | Professional & scientific | 2025 |
| Refine Consultancy Services Ltd | Professional & scientific | 2019 |
| Refine Skin Studios Ltd | Other services | 2026 |
| Reflect Apparel LLP | | 2024 |
| Reflection Powder Coaters Midlands Limited | Manufacturing | 2026 |
| Reflective Designs Limited | Manufacturing | 2002 |
| Reforest UK Limited | Professional & scientific | 2006 |
| Reform Brickworks Ltd | Construction | 2025 |
| Reforma Painting Solutions Ltd | Construction | 2024 |
| Reformatt Ltd | Manufacturing | 2024 |
| Reformer Strong Ltd | Other services | 2025 |
| Reframe Aesthetics Ltd | Other services | 2025 |
| Reframe Support Services Ltd | Professional & scientific | 2026 |
| Refresh Marketing Consultancy Limited | Professional & scientific | 2012 |
| Refurbish Right Ltd | Administrative & support | 2023 |
| Refurnishus Ltd | Extraterritorial | 2020 |
| REG Vardy (Property Management) Limited | Real estate | 1933 |
| REG Vardy (TMC) Limited | Wholesale & retail | 1923 |
| REG Vardy (TMH) Limited | Professional & scientific | 1993 |
| REG Vardy Limited | Wholesale & retail | 1958 |
| REG121 Ltd | Information & communication | 2026 |
| Regal Aluminium Limited | Construction | 2023 |
| Regal Cuts Ltd | Other services | 2025 |
| Regal Doors Ltd | Construction | 2013 |
| Regal Lanka Prime Holdings Ltd | Hospitality | 2025 |
| Regal Pride Ltd | Agriculture & fishing | 2024 |
| Regal Roof Systems Ltd | Construction | 2025 |
| Regatta Way Sports Club Ltd | Arts & recreation | 2026 |
| Regby Retail Limited | Wholesale & retail | 2020 |
| Regdem Limited | Wholesale & retail | 2025 |
| Regen Clothing Brand Limited | Manufacturing | 2024 |
| Regen Culture Wellness Ltd | Wholesale & retail | 2025 |
| Regen Medical Group Limited | Health & social care | 2019 |
| Regen Quest Ltd | Wholesale & retail | 2025 |
| Regency Auto Repairs Limited | Wholesale & retail | 2024 |
| Regency Court (Hunstanton) Management Limited | Households | 2025 |
| Regency Property Solutions Ltd | Real estate | 2024 |
| Regency Trade Limited | Wholesale & retail | 2018 |
| Regenerco Renewable Energy Limited | Energy | 2010 |
| Regent Apartments Ltd | Real estate | 2012 |
| Regent Court Barnsley Management Company Limited | Households | 2005 |
| Regent Estate Maintenance Limited | Construction | 2019 |
| Regent Home Builders Limited | Construction | 2021 |
| Regent Homes Limited | Extraterritorial | 2013 |
| Regent Inc. Limited | Professional & scientific | 2010 |
| Regent Motors Vehicle Sales Limited | Administrative & support | 2012 |
| Regent Street Automotive Limited | Wholesale & retail | 2008 |
| Regent Surveyors Ltd | Professional & scientific | 2025 |
| Regent Systems Ltd | Wholesale & retail | 2012 |
| Regents Housing Solutions Ltd | Real estate | 2025 |
| Regents Park Associates Limited | Financial services | 2003 |
| Reges Ltd | Administrative & support | 2019 |
| Reggae MAN Kitchen Limited | Hospitality | 2018 |
| Reggae Reggae Takeaway Ltd | Hospitality | 2025 |
| Reggie Pugh Limited | Professional & scientific | 2021 |
| Reggie Transport Ltd | Transport & logistics | 2025 |
| Regic Investments Ltd | Real estate | 2020 |
| Regina SUE Property Ltd | Real estate | 2019 |
| Regional Lightning Protection Ltd | Professional & scientific | 2022 |
| Regis Executive Transport Limited | Transport & logistics | 2025 |
| Rehab Beauty Limited | Other services | 2012 |
| Rehab Retreats Limited | Health & social care | 2015 |
| Rehabilitation Hub Ltd | Health & social care | 2020 |
| Rehoboath Ltd | Health & social care | 2022 |
| Rehoboth Care and Support Services Ltd | Health & social care | 2022 |
| Rehoboth Enterprise Limited | Real estate | 2016 |
| Rehoboth Therapy and Mentoring Services Ltd | Health & social care | 2025 |
| Rehoboth UK Homes Ltd | Real estate | 2020 |
| Reibles Limited | Real estate | 2026 |
| Reichenbach Strategy Limited | Professional & scientific | 2026 |
| Reid Physiotherapy Limited | Health & social care | 2016 |
| Reid Real Estate Ltd | Real estate | 2020 |
| Reid Rental Property LLP | | 2022 |
| Reid Software Limited | Information & communication | 2008 |
| Reids Investments Ltd | Arts & recreation | 2016 |
| Reign & Raine Interiors Design Management Ltd | Manufacturing | 2025 |
| Reigns, Property and Lettings Ltd | Real estate | 2023 |
| Reika Limited | Wholesale & retail | 2013 |
| Reilly's Construction Limited | Construction | 2023 |
| Reimagine Redefine Ltd | Professional & scientific | 2023 |
| Reimagining OUR Cast Offs Limited | Manufacturing | 2024 |