| Rbjm Healthcare Ltd | Health & social care | 2016 |
| RC Realisations 2025 Limited | Wholesale & retail | 2005 |
| Rcbrown Ltd | Professional & scientific | 2025 |
| RCF IT Solutions Ltd | Information & communication | 2025 |
| RCF Trading Ltd | Wholesale & retail | 2025 |
| RCI Contracting Ltd | Construction | 2024 |
| RCP Transport Limited | Transport & logistics | 2016 |
| RCS Healthcare Consulting Ltd | Professional & scientific | 2019 |
| Rdhcapital Ltd | Real estate | 2025 |
| RDL Properties Limited | Real estate | 2012 |
| Rdls Technical Services Limited | Construction | 2025 |
| Rdptrading Ltd | Construction | 2025 |
| RDS Fitness Limited | Arts & recreation | 2013 |
| RDS Houses Limited | Real estate | 2023 |
| Re:Solution Clinic Limited | Health & social care | 2015 |
| Readyworx Ltd | Construction | 2024 |
| Real Asset Market Intelligence Limited | Financial services | 2023 |
| Real Food Focus Ltd | Hospitality | 2025 |
| Real Inspiration CIC | Health & social care | 2018 |
| Realated Visual Limited | Arts & recreation | 2018 |
| Realisation by Design Ltd | Professional & scientific | 2006 |
| Reallymoving.Com Ltd. | Information & communication | 1999 |
| Rebuildit Limited | Professional & scientific | 2024 |
| Recfindr Ltd | Administrative & support | 2022 |
| Recharge Hospitality Limited | Administrative & support | 2016 |
| Reciprocal Holdings Limited | Financial services | 2026 |
| Reciprocal Management Partners Limited | Professional & scientific | 2011 |
| Red Admiral Productions Limited | Information & communication | 1997 |
| Red Agent Limited | Health & social care | 2022 |
| Red Alert PT Ltd | Arts & recreation | 2015 |
| Red Banana Design Limited | Professional & scientific | 2013 |
| Red Phone Consultants Limited | Professional & scientific | 2015 |
| Red PIN Capital Limited | Financial services | 2022 |
| Red Planet Projects Ltd | Water & waste | 2021 |
| Red Potato Limited | Professional & scientific | 2011 |
| Red Robin Property Ltd | Construction | 2018 |
| Red Robins Companion's Ltd | Health & social care | 2022 |
| Red Rock Five Ltd | Real estate | 2022 |
| Red Rock Physio Limited | Health & social care | 2014 |
| Red Ronin Studios Ltd | Information & communication | 2023 |
| Red Roquet Limited | Extraterritorial | 2009 |
| Red Star Formations Limited | Arts & recreation | 2015 |
| Red Supplies Limited | Wholesale & retail | 2019 |
| RED1AIRSOFT Limited | Wholesale & retail | 2008 |
| Redbourn Construction Limited | Construction | 2019 |
| Redbourn Electrical Contractors Limited | Construction | 2018 |
| Redbourn Eyecare Ltd | Health & social care | 2017 |
| Redbourn Hire Co. Ltd | Administrative & support | 2025 |
| Redbourn Rovers Football Club Ltd | Arts & recreation | 2025 |
| Redbourn Rovers Youth Football Club C.I.C. | Education | 2025 |
| Redbournbury Watermill Limited | Manufacturing | 2007 |
| Redbridge Financial Ltd | Financial services | 2016 |
| Redcone Recruitment Ltd | Administrative & support | 2022 |
| Redline International Freight Ltd | Transport & logistics | 2022 |
| Redrock Partners Ltd | Financial services | 2015 |
| Redshaws Limited | Real estate | 1997 |
| Redwood Lifetime Partners Limited | Financial services | 2013 |
| Reel Media Holdings Ltd. | Financial services | 2025 |
| Reel Media Specialty INS. Ltd. | Financial services | 2025 |
| Refine Labs Ltd | Information & communication | 2025 |
| Reflection Models Limited | Arts & recreation | 2021 |
| Reframe Design Ltd | Professional & scientific | 2026 |
| Refresh Projects Limited | Construction | 2020 |
| Refreshingly Clear Consulting Limited | Professional & scientific | 2023 |
| Refuel Performance Management Limited | Professional & scientific | 2012 |
| Refuel Performance Property Limited | Real estate | 2020 |
| Regal Choice Limited | Hospitality | 2018 |
| Regal Choice Property Ltd | Real estate | 2026 |
| Regal Choice Trading Ltd | Wholesale & retail | 2023 |
| Regal Garage Services Ltd | Wholesale & retail | 2008 |
| Regal Inventories Ltd | Real estate | 2021 |
| Regal-T Electrical Limited | Construction | 2021 |
| Regalvanize Ltd | Information & communication | 2024 |
| Regan Upton Property Limited | Real estate | 2024 |
| Regency Enforcement Ltd | Administrative & support | 2025 |
| Regency Lifesciences UK Ltd | Wholesale & retail | 2025 |
| Regency Way (Maintenance) Limited | Households | 2013 |
| Regent Memorial Ltd | Other services | 2013 |
| Regents Court Press Ltd | Information & communication | 2019 |
| Reid Roofing & Building Limited | Construction | 2017 |
| Reidentify Ltd | Professional & scientific | 2021 |
| Reika Botanics Ltd | Wholesale & retail | 2021 |
| REM Garden Maintenance Limited | Administrative & support | 2023 |
| Rembrandt London Limited | Wholesale & retail | 2017 |
| Renas Collection Ltd | Hospitality | 2025 |
| Rendham Marketing Services Limited | Administrative & support | 2014 |
| Rendr Ltd | Professional & scientific | 2020 |
| Renegade Fitness Academy Limited | Arts & recreation | 2016 |
| Renfin Glen Hydro Ltd | Financial services | 2018 |
| Renfin Hydro 4 Limited | Financial services | 2022 |
| Reniform Enterprises Limited | Other services | 2012 |
| Renny Exclusive Ltd | Manufacturing | 2011 |
| RENOV8TIONS Limited | Construction | 2012 |
| Renovite Technologies Limited | Information & communication | 2009 |
| Rent a Tent London Limited | Administrative & support | 2015 |
| Renzo Molinari Limited | Health & social care | 2004 |
| Replico Limited | Professional & scientific | 2007 |
| Reshape Builders Ltd | Construction | 2009 |
| Resilient at Heart CIC | Education | 2025 |
| Resin Surface Specialists Ltd | Administrative & support | 2018 |