| Red River Export Limited | Wholesale & retail | 2008 |
| Red Ronin Ltd | Professional & scientific | 2015 |
| Red Room Industries Limited | Professional & scientific | 2012 |
| Red Sea Construction Limited | Construction | 2022 |
| Red Sky Vision Ltd | Information & communication | 2005 |
| Red Tours Limited | Administrative & support | 2014 |
| Red USA Limited | Arts & recreation | 2026 |
| Red White Design Limited | Professional & scientific | 2010 |
| Red&Green Construct Ltd | Construction | 2019 |
| RED5 Investments Ltd | Real estate | 2024 |
| RED5 Medical Ltd | Health & social care | 2019 |
| Redberries CRM Limited | Professional & scientific | 2013 |
| Redbox Holdings Limited | Financial services | 2019 |
| Redbrick Estate Management Limited | Real estate | 2019 |
| Redbricks Capital Ltd | Real estate | 2021 |
| Redcat Events Ltd | Administrative & support | 2015 |
| Redcat I.T.Solutions Ltd | Information & communication | 2024 |
| Redcliffe Street Limited | Real estate | 2019 |
| Redcroft Heights Amenities Ltd | Households | 2020 |
| Redd Investments Management Ltd | Real estate | 2019 |
| Redeemer Technologies Limited | Information & communication | 2010 |
| Redefi Ltd | Financial services | 2022 |
| Redfin Consulting Services Limited | Information & communication | 2013 |
| Redhouse & Associates Business Services Limited | Professional & scientific | 1997 |
| Redlines Services Ltd | Professional & scientific | 2023 |
| Redman Pattni Limited | Professional & scientific | 2002 |
| Redmead Properties Limited | Real estate | 2015 |
| Redmoon Pictures Ltd | Information & communication | 2022 |
| Redomed Ltd | Wholesale & retail | 2026 |
| Redorange FLY UK Ltd | Wholesale & retail | 2025 |
| Redpath Financial Group Ltd | Financial services | 2021 |
| Redroof UK Limited | Wholesale & retail | 2009 |
| Redstar Trading Limited | Wholesale & retail | 1992 |
| Redthecha UK Ltd | Other services | 2025 |
| Reel Technology Ltd | Information & communication | 2025 |
| Reemca Ltd | Real estate | 2025 |
| Reenakrish Ltd | Real estate | 2023 |
| Reenat Consultants Limited | Health & social care | 2023 |
| Reevco Holdings Ltd | Real estate | 2025 |
| Reevten Ltd | Construction | 2026 |
| REF Investments Limited | Real estate | 2015 |
| Refab Ltd | Construction | 2026 |
| Refaeli Construction Ltd | Construction | 2018 |
| Refaeli Management Ltd | Construction | 2013 |
| Referral Finders Ltd | Information & communication | 2020 |
| Reflection Projects Limited | Professional & scientific | 2019 |
| Refluent AI Ltd | Information & communication | 2025 |
| Refrigeration & Air Conditioning Supplies Ltd | Construction | 2015 |
| Refurb Renovations Limited | Real estate | 2015 |
| Regal & Co Management Limited | Real estate | 2002 |
| Regal Builders Merchants Limited | Wholesale & retail | 2020 |
| Regal Consulting Services Limited | Information & communication | 2025 |
| Regal Everest Associates Limited | Health & social care | 2022 |
| Regal Gems and Jewellery Limited | Wholesale & retail | 2019 |
| Regal Health and Wellbeing Ltd | Health & social care | 2016 |
| Regal Healthcare Group Limited | Financial services | 2023 |
| Regal Housewares Limited | Wholesale & retail | 2015 |
| Regal Mare Limited | Manufacturing | 2011 |
| Regal Memoirs Limited | Administrative & support | 2025 |
| Regal Steels Limited | Wholesale & retail | 2024 |
| Regal Suite Holdings 2 Limited | Real estate | 2025 |
| Regal Suite Holdings Limited | Real estate | 2019 |
| Regal Support Ltd | Administrative & support | 2021 |
| Regal Way Management Limited | Real estate | 2011 |
| Regallite Properties Ltd | Real estate | 2022 |
| Regaltaste Limited | Real estate | 1995 |
| Rege on Limited | Wholesale & retail | 2025 |
| Regen LAB UK Ltd | Wholesale & retail | 2025 |
| Regency Airspace Ltd | Construction | 2021 |
| Regency Ascension Acquisitions Limited | Construction | 2023 |
| Regency Heights Management Company Limited | Households | 2003 |
| Regency Home Maintenance Ltd | Construction | 2024 |
| Regency Land Limited | Construction | 2002 |
| Regency UK Properties Limited | Hospitality | 2012 |
| Regent (London) Limited | Wholesale & retail | 1996 |
| Regent Connect UK Ltd | Administrative & support | 2024 |
| Regent Europe Ltd | Education | 2023 |
| Regents Estate (London) LLP | | 2015 |
| Regents Park Mews Limited | Real estate | 2021 |
| Region Hotels (Luton) Limited | Hospitality | 2013 |
| Regional & City Estates (Wherstead Road) Limited | Real estate | 2005 |
| Regis Properties(Uk) Ltd | Construction | 2020 |
| Regis UK Properties Ltd | Real estate | 2024 |
| Regulum Consulting Limited | Health & social care | 2024 |
| Regvision Pharma Consulting Ltd | Administrative & support | 2022 |
| Rehan Enterprizes Ltd | Wholesale & retail | 2022 |
| Rehmat - E - Shereen Limited | Hospitality | 2024 |
| Rehmey Ltd | Real estate | 2019 |
| REHMEY3 Ltd | Real estate | 2020 |
| Rehoboth Supported Living Ltd | Health & social care | 2025 |
| Rehoboth Trading Ltd | Administrative & support | 2020 |
| Reid Close Limited | Real estate | 2026 |
| Reigate Investments Limited | Real estate | 2006 |
| Reign Ventures Limited | Real estate | 2025 |
| Reikan Limited | Real estate | 2017 |
| Reiki Mindfulness Limited | Health & social care | 2015 |
| Reillyconsult Ltd | Professional & scientific | 2020 |
| Reina Polo Limited | Arts & recreation | 2002 |
| Reinsurance Consultants Limited | Information & communication | 2016 |
| Reiv Partners Ltd | Real estate | 2025 |