| Run Flat Systems Limited | Manufacturing | 2007 |
| Run Kaizen Ltd | Information & communication | 2022 |
| Runcheng Pack Co., Ltd | Extraterritorial | 2013 |
| Runehustle Ltd. | Information & communication | 2025 |
| Running With Crayons Limited | Information & communication | 2010 |
| Runtch Ltd | Wholesale & retail | 2025 |
| Runway Innovations Limited | Administrative & support | 2012 |
| Rural Asset Advisors Limited | Financial services | 2020 |
| Rural Asset Finance 1 Limited | Financial services | 2019 |
| Rural Asset Finance 2 Limited | Financial services | 2023 |
| Rural Asset Finance 3 Limited | Financial services | 2023 |
| Rural Asset Finance Group Limited | Financial services | 2026 |
| Rural Asset Finance Limited | Financial services | 2021 |
| Rural Asset Investments Limited | Financial services | 2024 |
| Rural Asset Management Services Limited | Financial services | 2016 |
| Rural Asset Operations Limited | Financial services | 2021 |
| Rural Senses Ltd | Professional & scientific | 2019 |
| RUS Akeniva Ecological Science Ltd | Mining & quarrying | 2025 |
| RUS Lamif International Fertilizer Co., Ltd | Mining & quarrying | 2025 |
| RUS Maimat Energy Huagong Group Co., Ltd | Mining & quarrying | 2024 |
| RUS Protia Mining Group Co., Ltd | Mining & quarrying | 2024 |
| RUS Wulaer Huagong Group Co., Ltd | Mining & quarrying | 2024 |
| Ruscarbonfiber Ltd | Manufacturing | 2026 |
| Rusen International Decoration Materials Co., Ltd | Manufacturing | 2025 |
| Rushingflow Limited | Information & communication | 2025 |
| Rushmere Farm (Gloucestershire) Limited | Real estate | 2022 |
| Rushton Aesthetics Limited | Health & social care | 2017 |
| Russell Gardens Management Company Ltd | Real estate | 2014 |
| Russia Chemicals Group Limited | Extraterritorial | 2017 |
| Russia Sural Sylvite Ltd | Mining & quarrying | 2023 |
| Rustat Property Company Limited | Real estate | 2003 |
| Rusty Enterprises Limited | Financial services | 2025 |
| Ruth Golombok Limited | Professional & scientific | 2013 |
| Rutherford Accountancy Limited | Professional & scientific | 2005 |
| Rutherford Punting Cambridge Ltd | Transport & logistics | 2019 |
| Rutherford Resources Limited | Professional & scientific | 2020 |
| Rutland Cars Limited | Transport & logistics | 2025 |
| Rvpv Family Office Limited | Administrative & support | 2014 |
| Rwaex Ltd | Financial services | 2025 |
| Rwrr (Holdings) Ltd | Financial services | 2024 |
| Rwtw Consulting LLP | | 2010 |
| Rxbiologics Limited | Professional & scientific | 2017 |
| Rxcelerate Limited | Professional & scientific | 2012 |
| Ryan Hutton Limited | Administrative & support | 2023 |
| RYB Newco Ltd | Information & communication | 2025 |
| Ryco Optics Ltd | Health & social care | 2007 |
| Rycroft-Smith & Macey Research Group Ltd | Professional & scientific | 2025 |
| Ryrr Ltd | Real estate | 2026 |
| RYS Citygate Limited | Real estate | 2017 |
| RYS Hotel Limited | Real estate | 2021 |
| RYS Kings Hedges Ltd | Real estate | 2017 |
| RYS Retail Ltd | Wholesale & retail | 2017 |
| RYS Sycamores Limited | Real estate | 2021 |
| Ryuki Limited | Hospitality | 2025 |
| RZ Intelligence Limited | Real estate | 2021 |
| RZC Transport Ltd | Transport & logistics | 2020 |
| Rêve DU Soir Ltd | Wholesale & retail | 2025 |
| S & a Medics Cambridge Limited | Health & social care | 2016 |
| S & J Sports Limited | Extraterritorial | 2025 |
| S & N Developers Limited | Construction | 2006 |
| S & P Mainlayers Limited | Construction | 2019 |
| S & R Medics Limited | Real estate | 2009 |
| S & Veer Haulage Ltd | Transport & logistics | 2023 |
| S a Rental Property Ltd | Real estate | 2019 |
| S and S Cleaning and Maintenance Services Limited | Other services | 2017 |
| S B Accounting (Cambridge) Limited | Professional & scientific | 2012 |
| S B Building & Carpentry Ltd | Construction | 2009 |
| S Boak Haulage Ltd | Water & waste | 2015 |
| S C Parker Building Contractors Ltd | Construction | 2021 |
| S Cradock TM Limited | Construction | 2024 |
| S F Shaukat Limited | Health & social care | 2013 |
| S G Controls Limited | Manufacturing | 1996 |
| S G Law Plumbing and Heating Ltd | Construction | 2019 |
| S Gale Services Limited | Other services | 2016 |
| S J F Property Services Ltd | Construction | 2025 |
| S J Gill Fencing Limited | Administrative & support | 2003 |
| S J Kilshaw Partners Ltd | Professional & scientific | 2016 |
| S J Marsh and Sons Building Limited | Construction | 2003 |
| S J Marsh and Sons Developments Limited | Construction | 2024 |
| S J Pollard Building & Maintenance Limited | Construction | 2019 |
| S King Ltd | Construction | 2015 |
| S M P Staircases Limited | Manufacturing | 2003 |
| S M Wilson Properties Ltd | Real estate | 2021 |
| S O'Hanlon Limited | Financial services | 2018 |
| S P Autos Cambs Ltd | Wholesale & retail | 2021 |
| S P N Consultancy Services Ltd. | Administrative & support | 2019 |
| S Sturgess Pubs Limited | Hospitality | 2019 |
| S W Carpentry Limited | Construction | 2019 |
| S W Hunt Consulting Limited | Information & communication | 2006 |
| S Wales Ltd | Administrative & support | 2024 |
| S Xpress BIO Limited | Professional & scientific | 2019 |
| S&B Herba Foods Limited | Manufacturing | 1919 |
| S&D Transfers Ltd | Transport & logistics | 2023 |
| S&Fm Developments Limited | Construction | 2021 |
| S&G Transport 1959 Ltd | Transport & logistics | 2023 |
| S&J Cambridge Fencing Ltd | Other services | 2025 |
| S&K Care Limited | Health & social care | 2013 |
| S&M(Cambs) Ltd | Construction | 2018 |
| S&S Development Ventures Limited | Construction | 2026 |
| S'Hail Metals UK Limited | Professional & scientific | 2017 |