| R & K Darts Merchandise Limited | Wholesale & retail | 2025 |
| R & L Bayley Associates Limited | Professional & scientific | 2013 |
| R & R Investment Management Limited | Real estate | 2022 |
| R & S Leisures Limited | Hospitality | 2008 |
| R C Automotive Herts Limited | Wholesale & retail | 2022 |
| R C Thermal Limited | Construction | 2015 |
| R Devitt Ltd | Real estate | 2022 |
| R J Chamberlain IT Consulting Limited | Information & communication | 2010 |
| R N Property Holdings Limited | Real estate | 2017 |
| R S N Lasers Limited | Health & social care | 2004 |
| R&A Family Properties Limited | Real estate | 2023 |
| R&N Hussein Ltd | Administrative & support | 2017 |
| R&P Agri Tech Ltd | Financial services | 2021 |
| R.F. Fairey & SON Limited | Construction | 2003 |
| R.J. Godefroy Limited | Administrative & support | 2003 |
| R.P.P Wiring Services Limited | Manufacturing | 2017 |
| R.R.K. Limited | Agriculture & fishing | 1978 |
| R.W. Unwin & Co. Limited | Wholesale & retail | 1965 |
| RA Fire and Safety Limited | Professional & scientific | 2015 |
| RA Property London Ltd | Real estate | 2020 |
| Rachel Childs Limited | Professional & scientific | 2022 |
| Rachel Evenden Mediation + Conflict Resolution Ltd | Health & social care | 2021 |
| Rachel Fyson Consulting Ltd | Professional & scientific | 2022 |
| Rachelogilvie Ltd | Administrative & support | 2019 |
| Radcliffe Road Hitchin Management Company Limited | Households | 2023 |
| Radec Engineering Limited | Professional & scientific | 1986 |
| Radi Kitchens & Bathrooms Ltd | Construction | 2015 |
| RAF Music Ltd | Arts & recreation | 2010 |
| Rafe Abrook Photography Limited | Professional & scientific | 2018 |
| RAILM5 Limited | Hospitality | 2021 |
| Rain Capital Ltd | Financial services | 2026 |
| Raise the Roof Properties Ltd | Real estate | 2023 |
| Raiyan Miah Ltd | Wholesale & retail | 2024 |
| RAJ Douth Curry Ltd | Hospitality | 2025 |
| RAJ Douth Tandoori Ltd | Hospitality | 2025 |
| Raju Embroidery Ltd | Manufacturing | 2022 |
| RAL Services Ltd | Administrative & support | 2026 |
| RAM Commercial Finance Ltd | Financial services | 2025 |
| Ramen Electra Ltd | Hospitality | 2022 |
| RAN Consultants Ltd | Professional & scientific | 2023 |
| Rance Landscapes Limited | Administrative & support | 2002 |
| Range Services Limited | Other services | 2018 |
| Rankin Consulting Limited | Administrative & support | 2024 |
| Ranscombe Cars Limited | Wholesale & retail | 1975 |
| Rapid Referrals Ltd | Professional & scientific | 2025 |
| Rara Limited | Real estate | 2018 |
| Rasi Properties Limited | Hospitality | 2018 |
| Rates Goblin Ltd | Information & communication | 2026 |
| Ravel Limited | Professional & scientific | 2015 |
| RAW Performance Group Ltd | Administrative & support | 2017 |
| RAW Performance Hitchin Limited | Arts & recreation | 2018 |
| RB Business Insights Limited | Professional & scientific | 2016 |
| RB Plumbing Limited | Construction | 2018 |
| RBS Hire and Sale Limited | Construction | 2017 |
| RBS Scaffolding Services Limited | Construction | 2008 |
| Rbttlx Ltd | Information & communication | 2023 |
| RCL Tattoo Limited | Other services | 2018 |
| RCW Property Holdings Ltd | Real estate | 2024 |
| RDA Psychology Practice Ltd | Health & social care | 2024 |
| Re-Certify Ltd | Wholesale & retail | 2020 |
| Re-Distribute Ltd | Wholesale & retail | 2021 |
| Read and Write VFX Limited | Information & communication | 2025 |
| Real Talk Holding Ltd | Financial services | 2025 |
| Real Talk Property Ltd | Real estate | 2025 |
| Realise Potential Ltd | Professional & scientific | 2010 |
| Realtyplus Ltd | Real estate | 2019 |
| Realworldkravmaga Ltd | Arts & recreation | 2026 |
| Reaper Drones Ltd | Information & communication | 2023 |
| Recapt Ltd | Information & communication | 2018 |
| Recruit With Ease Limited | Administrative & support | 2020 |
| Recruitfit Holdings Ltd | Financial services | 2024 |
| Recruitfit Ltd | Professional & scientific | 2016 |
| Rectory Management (Pirton) Limited | Households | 2000 |
| Red Apple Cuisine Limited | Extraterritorial | 2012 |
| Red Earth Consulting Limited | Information & communication | 2017 |
| Red Kalahari Limited | Wholesale & retail | 2020 |
| Red Lion BWG Limited | Hospitality | 2018 |
| Red Maple Holdings Ltd | Professional & scientific | 2025 |
| Red Media Love CIC | Education | 2022 |
| Red Penguin Photography Limited | Professional & scientific | 2019 |
| Red Rose Learning LLP | | 2025 |
| Red ZED Films Limited | Administrative & support | 2004 |
| Redart Camden Ltd | Real estate | 2018 |
| Redbourn Express Services Limited | Transport & logistics | 1999 |
| Redbourn Group Limited | Real estate | 1987 |
| Redbourn Holdings Limited | Professional & scientific | 2009 |
| Redel Limited | Other services | 2017 |
| Redoubt Close Management Limited | Real estate | 1999 |
| Redreef Ltd | Administrative & support | 2015 |
| Redshed Design Limited | Professional & scientific | 2019 |
| Redwood Energy Limited | Professional & scientific | 1997 |
| Redz Trading Ltd | Wholesale & retail | 2023 |
| Reficio Limited | Professional & scientific | 2003 |
| Refind Software Limited | Information & communication | 2005 |
| Refine Education Ltd | Administrative & support | 2026 |
| Refined Interiors Ltd | Construction | 2024 |
| Refined Landscapes Ltd | Administrative & support | 2018 |
| Reflair Ltd | Information & communication | 2023 |
| Reflex Investments Ltd | Financial services | 2022 |
| Refraction HR Ltd | Administrative & support | 2025 |