| Red Eagle Buses Limited | Transport & logistics | 2013 |
| Red Gents Barbers (Hale Leys) Ltd | Other services | 2018 |
| Red Group Properties Ltd | Financial services | 2019 |
| Red Helix Cyber Services Limited | Information & communication | 2024 |
| Red Helix Limited | Information & communication | 1984 |
| Red Iguana Associates Ltd | Hospitality | 2012 |
| Red Kite Energy Limited | Professional & scientific | 2015 |
| Red Kite Radio and Media Limited | Information & communication | 2015 |
| Red Kyte Print Limited | Administrative & support | 2013 |
| Red Light Sales and Marketing Limited | Professional & scientific | 2018 |
| Red Line Buses Ltd | Transport & logistics | 2013 |
| Red Monster Ltd | Agriculture & fishing | 2025 |
| Red Moon Forty Seven Ltd | Professional & scientific | 2024 |
| Red Rolls Ltd | Other services | 2014 |
| Red Rose Travel Limited | Transport & logistics | 1994 |
| Red Square Online Ltd | Wholesale & retail | 2012 |
| Red Squirrel 22 Consultancy Ltd | Professional & scientific | 2023 |
| Red Tree (2004) LLP | | 2004 |
| Red Tree Properties Limited | Administrative & support | 2013 |
| Red Trident Limited | Real estate | 2016 |
| Redbush Entertainment Limited | Other services | 2010 |
| Redcote Properties Ltd | Real estate | 2002 |
| Reddie Maintenance Services Ltd | Professional & scientific | 2019 |
| Redefine Ecom Limited | Professional & scientific | 2023 |
| Redesign Webdesign Limited | Information & communication | 2015 |
| Redhill Design & Construction Limited | Construction | 2019 |
| Redkim Ltd | Health & social care | 2018 |
| Redleaves Collett Ltd | Professional & scientific | 2022 |
| Redline Servicing Limited | Wholesale & retail | 2006 |
| Redoctane Games Limited | Information & communication | 2025 |
| Redoctane Labs Limited | Manufacturing | 2002 |
| Redse Ltd | Health & social care | 2024 |
| Redstar Marketing Ltd | Professional & scientific | 2025 |
| Redux Cinema Limited | Information & communication | 2021 |
| Redvale Services Limited | Administrative & support | 2003 |
| Redwood BMS Limited | Administrative & support | 2019 |
| Reed and Harris Ltd | Professional & scientific | 2026 |
| Reejust Creations Limited | Wholesale & retail | 2021 |
| Reel Thing Events Ltd | Administrative & support | 2023 |
| Reena Cafe Limited | Hospitality | 2022 |
| Rees Building Services Ltd | Construction | 2011 |
| Reeshar Limited | Arts & recreation | 2020 |
| Reeve Group Ltd | Wholesale & retail | 2025 |
| Reflectears Limited | Health & social care | 2016 |
| Refthebarber Limited | Other services | 2023 |
| Regal Builders Limited | Construction | 2010 |
| Regalbourne Trading Limited | Administrative & support | 2017 |
| Regansoft Ltd | Information & communication | 2016 |
| Regent Property Developments & Accommodations Limited | Hospitality | 2019 |
| Regions & Counties Property Management Limited | Real estate | 2024 |
| Regnant Limited | Wholesale & retail | 2017 |
| Regulus Bidco Limited | Financial services | 2015 |
| Rejak Limited | Information & communication | 1998 |
| Relentless Doors Ltd | Construction | 2021 |
| Reliance Pension Scheme Trustee Limited | Financial services | 1983 |
| Relleom Holdings Limited | Financial services | 2024 |
| Remald Investments Limited | Financial services | 2018 |
| Remconstruct Ltd | Construction | 2023 |
| Remedial Studio Ltd | Health & social care | 2022 |
| REMEDY24 Ltd | Health & social care | 2023 |
| Ren-Rc Ltd | Public administration | 2024 |
| Renew Spaces Ltd | Construction | 2023 |
| Renewables PM Ltd | Professional & scientific | 2015 |
| Renokit Ltd | Information & communication | 2023 |
| Renova Aesthetic Ltd | Other services | 2025 |
| Renovate Building Sols Ltd | Construction | 2019 |
| Renovio Ltd | Construction | 2022 |
| Rent Local Ltd | Real estate | 2026 |
| Rente Ltd | Wholesale & retail | 2025 |
| Rentedge Ltd | Real estate | 2025 |
| Renuka Solutions Ltd | Information & communication | 2024 |
| Reorapetse Trading Limited | Professional & scientific | 2024 |
| Repc Solutions Ltd | Other services | 2007 |
| Represence Ltd | Other services | 2025 |
| Reprogram Limited | Real estate | 2014 |
| Republic of Cats Limited | Manufacturing | 2024 |
| Residual Electrical Ltd | Construction | 2021 |
| Resilient Locums Limited | Health & social care | 2023 |
| Resilient Systems Limited | Professional & scientific | 2025 |
| Resodyn Europe Limited | Professional & scientific | 2019 |
| Resonant Solutions Limited | Professional & scientific | 2001 |
| Rest and Restore Homes Ltd | Real estate | 2025 |
| Resting Humans Community Interest Company | Education | 2020 |
| Restituo TE Ltd | Health & social care | 2022 |
| Retail Media Works Ltd | Information & communication | 2023 |
| Rethink-Hseq Limited | Professional & scientific | 2026 |
| Retropro Energy Ltd | Professional & scientific | 2025 |
| Retsof Design Ltd | Professional & scientific | 2020 |
| Revamp Painting & Decorating Limited | Construction | 2025 |
| Revenue Finders Limited | Professional & scientific | 2022 |
| Revenue Protect Limited | Information & communication | 2006 |
| Reversion Flat 6 Gloucester Square Limited | Households | 2008 |
| Revival Blue Limited | Administrative & support | 1993 |
| Revival Commercial Limited | Other services | 1988 |
| Revival Group Limited | Administrative & support | 2002 |
| Revo Property Ltd | Real estate | 2011 |
| Revolutionary Consultancy Ltd | Information & communication | 2024 |
| Revolve Consulting Ltd | Professional & scientific | 2023 |
| Revolver Express Ltd | Transport & logistics | 2025 |
| Revops Catalyst Limited | Professional & scientific | 2023 |