| Rebotic Limited | Administrative & support | 2019 |
| Rebuild Healing Ministry Ltd | Other services | 2025 |
| Rebuild International Ltd | Construction | 2023 |
| Recall Security Limited | Administrative & support | 2020 |
| Recell and Renew Limited | Wholesale & retail | 2025 |
| Recequity Ltd | Professional & scientific | 2025 |
| Reclassification CIC | Education | 2025 |
| Recon Property Management Limited | Construction | 2025 |
| Reconnect - Outreach & Training Ltd | Health & social care | 2025 |
| Reconstruct Harpenden Ltd | Construction | 2024 |
| Recova Limited | Other services | 2024 |
| Recovary by Kata Ltd | Wholesale & retail | 2025 |
| Recoveryguys Ltd | Transport & logistics | 2025 |
| Recraft London Limited | Real estate | 2021 |
| Recruiting Teachers Abroad Ltd | Administrative & support | 2024 |
| Recruitment and Development Limited | Education | 2018 |
| Recruitment Partners Solution Ltd | Wholesale & retail | 2023 |
| Recur Global Limited | Information & communication | 2010 |
| Recur Services Limited | Other services | 2012 |
| Recut Collective Limited | Information & communication | 2021 |
| Red & Black Freeholds Limited | Real estate | 2019 |
| Red & Black Holdings Limited | Professional & scientific | 2020 |
| Red & Black Limited | Real estate | 2015 |
| Red Acer Homes Ltd | Real estate | 2023 |
| Red Anaar Ltd | Wholesale & retail | 2026 |
| Red and Black Developments Limited | Real estate | 2014 |
| Red and Black Group Limited | Financial services | 2019 |
| Red Balloon Developments Ltd | Real estate | 2017 |
| Red Brick House Ltd | Real estate | 2018 |
| Red Chilli Restaurant (Luton) Limited | Hospitality | 2008 |
| Red First Aviation Ltd | Manufacturing | 2025 |
| Red Garnet Properties Ltd | Real estate | 2019 |
| Red Hair Dressers Ltd | Other services | 2023 |
| Red HC Limited | Wholesale & retail | 2020 |
| Red Hot Competitions Limited | Arts & recreation | 2025 |
| Red Hot Fashion Empire Academy Limited | Education | 2025 |
| Red HP Limited | Real estate | 2022 |
| Red Lilies Ltd | Real estate | 2023 |
| Red Lion London Limited | Real estate | 2025 |
| Red Oak Property Group Ltd | Real estate | 2021 |
| Red Rooster Peri Peri Ltd | Hospitality | 2013 |
| Red Rose Recruitment UK Ltd | Administrative & support | 2017 |
| Red Shield Property Ltd | Real estate | 2024 |
| Red Spartan Limited | Wholesale & retail | 2016 |
| Red Squirrel Drone Services Ltd | Professional & scientific | 2026 |
| Red Tree Property Group Ltd | Real estate | 2025 |
| Redditor Ltd | Information & communication | 2024 |
| Redesign HQ Ltd | Construction | 2024 |
| Redesignsport Limited | Professional & scientific | 2013 |
| Redgate Farm Limited | Real estate | 2025 |
| Redgills Trading Limited | Information & communication | 2025 |
| Redglade Associates Limited | Real estate | 2004 |
| Redglade Investments Ltd | Professional & scientific | 2005 |
| Redharbour Holding Ltd | Professional & scientific | 2025 |
| Redline Contract Recruitment Limited | Professional & scientific | 2002 |
| Redline Driving School Ltd | Education | 2025 |
| Redline Executive Limited | Administrative & support | 2017 |
| Redline Group Limited | Administrative & support | 1982 |
| Redmint Investments Ltd | Real estate | 2018 |
| Reds Rejuvenation Ltd | Other services | 2025 |
| Redwan and Sons Ltd | Wholesale & retail | 2018 |
| Redwire Electrical Ltd | Construction | 2026 |
| Reed Place (Harpenden) Management Company Ltd | Real estate | 2024 |
| Reedaq Holdings Ltd | Real estate | 2021 |
| Reedaq Invest Ltd | Real estate | 2025 |
| Reem Homes Ltd | Real estate | 2025 |
| Reem Homes Sales and Lettings Ltd | Real estate | 2026 |
| Reeves Rescue Ltd | Transport & logistics | 2017 |
| Reeya Treatz Ltd | Hospitality | 2023 |
| Refer and Partner Ltd | Information & communication | 2025 |
| Refixer Limited | Wholesale & retail | 2026 |
| Reflections Computer Services Limited | Information & communication | 2001 |
| Reflexions Limited | Information & communication | 2004 |
| Reform Bathrooms and Kitchens Ltd | Construction | 2019 |
| Refugee and Migrant Development Association | Education | 2018 |
| Refurbspot Ltd | Information & communication | 2025 |
| REG Ability Ltd | Professional & scientific | 2024 |
| REG Locker Ltd | Wholesale & retail | 2020 |
| Regain Strength Physiotherapy Ltd | Other services | 2025 |
| Regal & Lancer Investments Limited | Real estate | 2025 |
| Regal Core UK Ltd | Administrative & support | 2024 |
| Regal Development Solutions Ltd | Construction | 2000 |
| Regal Excellence Security Ltd | Administrative & support | 2025 |
| Regal International Services Limited | Construction | 2024 |
| Regal Luroqhe Worldwide Ltd | Wholesale & retail | 2025 |
| Regal Pride E Liquids Ltd | Other services | 2018 |
| Regale Ltd | Hospitality | 2024 |
| Regency Developments Luton Ltd | Construction | 2020 |
| Regency Drylining Ltd | Construction | 2025 |
| Regency Properties Management Ltd | Real estate | 2015 |
| Regency Property Management(Uk) Limited | Real estate | 2018 |
| Regenera Hair Restoration Clinic Ltd | Other services | 2026 |
| Regent Court Management (Luton) Limited | Households | 2007 |
| Regent Fire and Security Ltd | Construction | 2023 |
| Regent Gate Ltd | Real estate | 2023 |
| Regent Gate Properties Limited | Real estate | 2024 |
| Regent Leasing Limited | Administrative & support | 2016 |
| Regent Link Exports Limited | Wholesale & retail | 2025 |
| Regent Protection Services Ltd | Administrative & support | 2016 |
| Reggae Rush Limited | Hospitality | 2025 |