| Rigit Mast and Rigging UK Limited | Manufacturing | 2020 |
| Rigmanic Ltd | Information & communication | 2024 |
| Rigmap Ltd | Information & communication | 2011 |
| Rimas Plant Ltd | Construction | 2018 |
| Rimm Technologies Limited | Wholesale & retail | 2019 |
| Rimont Limited | Real estate | 2016 |
| Rina UK Limited | Professional & scientific | 1999 |
| Ring Skins Limited | Wholesale & retail | 2016 |
| Ringos Bagle House Ltd | Extraterritorial | 2023 |
| Ringtail Limited | Professional & scientific | 2018 |
| RIO M Transport Ltd | Transport & logistics | 2026 |
| Rios Piri Piri Southampton Ltd | Hospitality | 2020 |
| Rios Portswood Ltd | Hospitality | 2025 |
| Rios Properties Ltd | Real estate | 2022 |
| Riovideo Ltd | Wholesale & retail | 2013 |
| Ripit Limited | Professional & scientific | 2021 |
| Ripmax Limited | Wholesale & retail | 1949 |
| Riptorn Ltd | Manufacturing | 2025 |
| Riraki Limited | Construction | 2024 |
| Rise and Shine Serviced Apartments Limited | Hospitality | 2018 |
| Rise Construction & Developments Ltd | Construction | 2025 |
| Risk & Protect K9 Security Ltd | Public administration | 2023 |
| Risk Research & Consulting (UK) Limited | Education | 2011 |
| Risovent Ltd | Information & communication | 2023 |
| Rita's at the Point Ltd | Hospitality | 2025 |
| Rita's in the Park Ltd | Hospitality | 2023 |
| Rivaaj Ltd | Wholesale & retail | 2014 |
| Rival South Ltd | Information & communication | 2013 |
| Rivatech Solutions Limited | Wholesale & retail | 2013 |
| Rivendale Acquisitions LLP | | 2014 |
| Rivendale Commercial Properties Ltd | Construction | 2019 |
| Rivendale Construction Limited | Construction | 2000 |
| Rivendale Developments Ltd | Construction | 2008 |
| Rivendale Holding Group Ltd | Financial services | 2020 |
| Rivendale Homes Ltd | Extraterritorial | 2008 |
| River Consultancy Limited | Information & communication | 2003 |
| River Green Management Limited | Households | 1962 |
| River Hamble Holdings Ltd | Financial services | 2019 |
| River Hamble Investments Ltd | Financial services | 2019 |
| River Heights Limited | Health & social care | 2005 |
| River Inns Limited | Hospitality | 2020 |
| River Itchen Homes Limited | Real estate | 2021 |
| River Knight Limited | Information & communication | 2023 |
| River Lane Services Ltd | Administrative & support | 2021 |
| River Meon Business Park Limited | Real estate | 2024 |
| River Stays Ltd | Hospitality | 2024 |
| River Studio (Warsash) Limited | Manufacturing | 2021 |
| Riverbank Legal UK Ltd | Administrative & support | 2026 |
| Riverbank Solutions Ltd | Professional & scientific | 2015 |
| Riverbank Studios Limited | Extraterritorial | 2003 |
| Riverdene Ventures Limited | Administrative & support | 2015 |
| Rivermead Marketing Limited | Wholesale & retail | 1996 |
| Riverport Capital Limited | Construction | 2021 |
| Rivers Project Management Company Limited | Professional & scientific | 2012 |
| Riversdown Services Limited | Education | 1983 |
| Riverside Bifolds Limited | Manufacturing | 2012 |
| Riverside Court (Bitterne) Management Limited | Households | 1982 |
| Riverside Electrical & PAT Testing Ltd | Construction | 2024 |
| Riverside House Management Company (ST Denys, Southampton) Limited | Households | 2008 |
| Riverside Precision Engineering Ltd | Professional & scientific | 2017 |
| Riverside Remnants & Innovation Ltd | Professional & scientific | 2015 |
| Riverside Social Ltd | Hospitality | 2024 |
| Riverside Storage and Rentals LLP | | 2016 |
| Riverside Tax Advisors Limited | Professional & scientific | 2023 |
| Riverside Windows Direct Ltd | Manufacturing | 2019 |
| Riversouthshop Ltd | Wholesale & retail | 2023 |
| Riverwood House (NH) Limited | Health & social care | 2025 |
| Rixit Liquor Merchant Limited | Wholesale & retail | 2025 |
| RIZ Kidz Toddz Ltd | Health & social care | 2024 |
| Riz's Taxi Limited | Transport & logistics | 2024 |
| Rizmos Ltd | Information & communication | 2025 |
| Rizz Stores Ltd | Wholesale & retail | 2024 |
| RJ Civil Engineering Solutions Ltd | Construction | 2020 |
| RJ Composites Limited | Manufacturing | 2022 |
| RJ Motors & Mot’S Limited | Wholesale & retail | 2023 |
| RJ Properties (South) Ltd | Real estate | 2024 |
| RJ Rail Solutions Ltd | Professional & scientific | 2018 |
| RJ Recovery Services Limited | Transport & logistics | 2025 |
| RJ Thind Builders Ltd | Construction | 2019 |
| RJ Yacht Lifting Limited | Transport & logistics | 2011 |
| RJB Plumbing & GAS Services Ltd | Construction | 2011 |
| RJB PUB Co Ltd | Hospitality | 2026 |
| RJB Vehicle Transport and Recovery Ltd | Transport & logistics | 2023 |
| RJG Carpentry Limited | Manufacturing | 2026 |
| Rjhanna Property Limited | Financial services | 2022 |
| RJK Plumbers Ltd | Construction | 2022 |
| RJM Manufacturing (Hampshire) Limited | Professional & scientific | 2021 |
| RJP Wealth Planning Ltd | Financial services | 2014 |
| RJR Design Solutions Ltd | Professional & scientific | 2022 |
| RJS Outfitting Ltd | Manufacturing | 2024 |
| RJS Properties (Hampshire) Ltd | Real estate | 2021 |
| RJS Subsea Ltd | Construction | 2020 |
| RJW Property Consultants Ltd | Administrative & support | 2011 |
| RK Building Design Ltd | Professional & scientific | 2021 |
| RK Security Solutions Limited | Administrative & support | 2012 |
| RK Trade Links Ltd | Construction | 2025 |
| RK Ventures Inc. UK Limited | Wholesale & retail | 2017 |
| RK9 Handling Ltd | Administrative & support | 2025 |
| RKB Composites Ltd | Manufacturing | 2018 |
| RKC Shedfield Holdings Ltd | Financial services | 2026 |