| Reachit Solutions Limited | Professional & scientific | 2018 |
| Read Educational & Child Psychology Ltd | Education | 2026 |
| Ready for Business Ltd | Information & communication | 2020 |
| Real Harbour Capital Limited | Real estate | 2025 |
| Real Logistics Services Ltd | Information & communication | 2018 |
| Real Supplements Ltd | Wholesale & retail | 2026 |
| Real Time Resourcing Ltd | Construction | 2026 |
| Realia Ltd | Professional & scientific | 2005 |
| Realipm (UK) Ltd | Wholesale & retail | 2014 |
| Realising Designs Limited | Information & communication | 2009 |
| Reality Network Services Ltd | Information & communication | 2001 |
| Reality Telecom Ltd | Information & communication | 2012 |
| Rebel Drinks (London) Limited | Manufacturing | 2014 |
| Reborn UK Properties Ltd | Real estate | 2022 |
| Rebound Coffee Ltd | Hospitality | 2025 |
| Rebourne Fabrications Limited | Manufacturing | 2025 |
| Recall Labs Limited | Information & communication | 2026 |
| Reco Pro Limited | Extraterritorial | 2015 |
| Reco Ready MIX Limited | Manufacturing | 2019 |
| Recomix Limited | Manufacturing | 2019 |
| Recreate Toys Limited | Wholesale & retail | 2021 |
| Recruit Staff Limited | Professional & scientific | 1996 |
| Recruitment Holdings Limited | Administrative & support | 1987 |
| Recruitment JV S International Limited | Professional & scientific | 2002 |
| Recruitment Solutions (Folkestone) Limited | Administrative & support | 2002 |
| Red Akita Rigging Ltd | Construction | 2024 |
| Red Alert Telecare Limited | Wholesale & retail | 2007 |
| Red Alert Telehealth Ltd | Professional & scientific | 2010 |
| Red and White Agency UK Limited | Professional & scientific | 2025 |
| Red Berry Recruitment Ltd | Professional & scientific | 2001 |
| Red BOW Property Solutions Limited | Real estate | 2021 |
| Red Button Lifeline Limited | Extraterritorial | 2014 |
| Red Button Telecare Limited | Wholesale & retail | 2014 |
| Red Capybara Ltd | Information & communication | 2023 |
| Red Cube Property Solutions Limited | Professional & scientific | 2009 |
| Red Dragon Digital Media Limited | Manufacturing | 2010 |
| Red Dragon I.T. Limited | Information & communication | 2004 |
| Red Dragon Web Design Limited | Information & communication | 2011 |
| Red Flag Safety Limited | Administrative & support | 2021 |
| Red Luna Removals Ltd | Water & waste | 2026 |
| Red MAN Solutions Limited | Administrative & support | 2013 |
| Red Peter Productions Limited | Administrative & support | 2025 |
| Red Pill Data Ltd | Information & communication | 2020 |
| Red Property UK Limited | Public administration | 2004 |
| Red Squirrel Accounting Ltd | Professional & scientific | 2018 |
| Red TAP Pubs Limited | Hospitality | 2023 |
| Red to Black Retail Consultancy Limited | Administrative & support | 2016 |
| Redbreast Holdings Limited | Financial services | 2023 |
| Redbrick AI Limited | Information & communication | 2026 |
| Redbridge School Sports Collective CIC | Education | 2024 |
| Reddy & Swamy Limited | Administrative & support | 2012 |
| Redec Limited | Construction | 1994 |
| Redec Refurbishment Limited | Construction | 2015 |
| Redefined by Kate Ltd | Other services | 2026 |
| Redesign Labs Ltd | Professional & scientific | 2022 |
| Redstone Residential Ltd | Households | 2014 |
| Redtap Ventures Limited | Professional & scientific | 2022 |
| Redtile Investment Limited | Real estate | 2020 |
| Redwood Valley Films Limited | Information & communication | 2025 |
| Redwood Vehicle Management Consultants Limited | Financial services | 1997 |
| Redwood Wealth Limited | Professional & scientific | 2025 |
| Redyear Court Management Company Limited | Households | 1988 |
| REE 503 Limited | Real estate | 2020 |
| Reece Social Care Ltd | Hospitality | 2019 |
| Reed Buckingham Ltd | Professional & scientific | 2015 |
| Reedsfield Care Ltd | Health & social care | 2013 |
| Reedsfield Road Management Limited | Households | 2006 |
| Reena RAJ Travels Ltd | Hospitality | 2025 |
| Reeves & GUY Enterprises Ltd | Hospitality | 2018 |
| Refactor Ltd | Extraterritorial | 2016 |
| Refined Homes Ltd | Construction | 2022 |
| Refrater Ltd | Information & communication | 2026 |
| Refresh 4 Rent Limited | Administrative & support | 2026 |
| Regal Bluesprings Services Limited | Wholesale & retail | 2025 |
| Regal Delights Ltd | Wholesale & retail | 2024 |
| Regal Rooflines (South East) Limited | Construction | 2021 |
| Regal Rooflines Kent Limited | Construction | 2022 |
| Regency (Support Services) Limited | Financial services | 2004 |
| Regency Group Offshore Ltd | Manufacturing | 2025 |
| Regency House Residents Limited | Real estate | 1992 |
| Regency Residential Property Management Ltd | Real estate | 2026 |
| Regency Response Ltd | Construction | 2024 |
| Regency Services Essex Limited | Construction | 2018 |
| Regent Coaches Limited | Extraterritorial | 1999 |
| Regional Property Auctioneering Limited | Extraterritorial | 2013 |
| Regional Property Auctioneers Limited | Extraterritorial | 2013 |
| Regnum Developments Ltd | Construction | 2013 |
| Regroup Operations Limited | Administrative & support | 2016 |
| Rehear Ltd | Health & social care | 2014 |
| Reichardt Services Limited | Professional & scientific | 2020 |
| Reka Building Ltd | Construction | 2026 |
| Reka Family Estates Limited | Real estate | 2024 |
| Relax Productions Limited | Information & communication | 2025 |
| Release Freedom Limited | Financial services | 2020 |
| Relentless Talent Limited | Information & communication | 2003 |
| Reliable Contractors Limited | Construction | 2002 |
| Reliable Power International Ltd | Energy | 2024 |
| Reliable Storage Ltd | Transport & logistics | 2021 |
| Reliablerent Ltd | Information & communication | 2026 |
| Relibuild UK Ltd | Construction | 2025 |