| Sustainable Motorsport Alliance | Administrative & support | 2025 |
| Sustainable Process Excellence Solutions Limited | Professional & scientific | 2018 |
| Sutch Catering Limited | Hospitality | 2019 |
| Sutch Lifting Equipment Limited | Wholesale & retail | 1998 |
| Suyrt Limited | Information & communication | 2012 |
| Suzgo Services Limited | Health & social care | 2023 |
| Suzie's Pets Ltd | Other services | 2023 |
| Suzy Wootton Voices Limited | Administrative & support | 2009 |
| SV Bude Development Ltd | Hospitality | 2016 |
| SV Bude Five Ltd | Real estate | 2025 |
| SV Bude Four Ltd | Real estate | 2026 |
| SV Bude One Ltd | Real estate | 2017 |
| SV Bude Three Limited | Real estate | 2017 |
| SV Bude Two Ltd | Extraterritorial | 2017 |
| SV Engineering Ltd | Manufacturing | 2018 |
| Svelliott Ltd | Hospitality | 2020 |
| Sveta Gholde Services Ltd | Information & communication | 2022 |
| Svetshine Cleaning Ltd | Administrative & support | 2025 |
| SVG Brickwork Ltd | Construction | 2022 |
| SVG Transport Logistic Ltd | Transport & logistics | 2021 |
| Svjs Construction Ltd | Construction | 2025 |
| SVR Enterprise Ltd | Hospitality | 2018 |
| SVT Brickgroup Ltd | Construction | 2026 |
| SW & RH Properties Limited | Real estate | 2020 |
| SW Dermatology Ltd | Health & social care | 2026 |
| SW Itsm Ltd | Information & communication | 2023 |
| SW Suspension Ltd | Wholesale & retail | 2021 |
| Swag Shop (London) Limited | Construction | 1993 |
| Swaham Limited | Information & communication | 2014 |
| Swainbank Capital Ltd | Real estate | 2025 |
| Swam Media Ltd | Manufacturing | 2015 |
| Swan Barrett LLP | | 2009 |
| Swan Cleaning Services (Northampton) Limited | Administrative & support | 2016 |
| Swan Enviro Limited | Manufacturing | 2000 |
| Swan Events Limited | Administrative & support | 2009 |
| Swan Hire Services Limited | Administrative & support | 2019 |
| Swan Holdings 813 Ltd | Real estate | 2024 |
| Swan Lake Capital Management Limited | Financial services | 2017 |
| Swan Pham Luong Investments Limited | Real estate | 2020 |
| Swan Press (Northampton) Limited | Real estate | 1935 |
| Swan Valley Legal Ltd | Professional & scientific | 2021 |
| Swanley Village Vineyard Limited | Professional & scientific | 2006 |
| Swanswell Properties Bude Ltd | Real estate | 2017 |
| Swanswell Properties Cornwall Ltd | Real estate | 2017 |
| Swanswell Properties Limited | Construction | 2005 |
| Swanswell Property Five Ltd | Construction | 2026 |
| Swanswell Property Four Ltd | Construction | 2026 |
| Swanswell Property One Ltd | Real estate | 2026 |
| Swanswell Property Three Ltd | Construction | 2026 |
| Swanswell Ventures Limited | Extraterritorial | 2017 |
| Swaralathika Limited | Arts & recreation | 2026 |
| Sweat Promotions Limited | Hospitality | 2000 |
| Sweeney Holdings Limited | Professional & scientific | 2017 |
| Sweeping Beauty ( Northampton) Limited | Administrative & support | 2015 |
| Sweeping Beauty Commercial (Northampton) Ltd | Administrative & support | 2022 |
| Sweet Chariot Consulting Limited | Professional & scientific | 2008 |
| Sweet Gains Ltd | Hospitality | 2019 |
| Sweet Machine News Limited | Wholesale & retail | 2007 |
| Sweet Place Limited | Hospitality | 2016 |
| Sweetheart Nannies Ltd | Health & social care | 2022 |
| Sweven Studio Ltd | Wholesale & retail | 2022 |
| Sweya Group Ltd | Other services | 2026 |
| Swf&Co Ltd | Wholesale & retail | 2025 |
| SWI Holdings Limited | Financial services | 2018 |
| Swift Anaesthesia Ltd | Health & social care | 2023 |
| Swift Cargo Ltd | Transport & logistics | 2023 |
| Swift Motion Executive Cars Ltd | Transport & logistics | 2022 |
| Swift Shuttles Services Ltd | Wholesale & retail | 2026 |
| Swift&Simple Logistics Ltd. | Transport & logistics | 2022 |
| Swiftclear Ltd | Transport & logistics | 2025 |
| Swiftlend Limited | Financial services | 2025 |
| Swiftreach Logistics and Marketing Limited | Wholesale & retail | 2025 |
| Swifttech Solutions Ltd | Information & communication | 2015 |
| Swim Acceleration Limited | Other services | 2013 |
| Swim Pools & Spas Ltd | Construction | 2022 |
| Swimcube Open Water Ltd | Arts & recreation | 2023 |
| Swinkeu and Sons Ltd | Professional & scientific | 2016 |
| Swiped on Limited | Extraterritorial | 2014 |
| Swish Culture Ltd | Manufacturing | 2024 |
| Swiss Build Limited | Construction | 2015 |
| Swiss Electrical Ltd | Construction | 2024 |
| Switch Lighting Limited | Information & communication | 2017 |
| Switchbus Ltd | Transport & logistics | 2021 |
| Swivel Healthcare Ltd | Administrative & support | 2021 |
| SWL Healthcare Limited | Manufacturing | 2023 |
| Swyp Limited | Administrative & support | 2019 |
| SXR Laboratories Limited | Professional & scientific | 2025 |
| Sybaritic Property Limited | Hospitality | 2017 |
| Sybaritic Pubs Limited | Hospitality | 2023 |
| Sycamore Advisory Limited | Professional & scientific | 2019 |
| Sycamore Group Holdings Limited | Financial services | 2026 |
| Sycamores Management (Leicester) Limited | Households | 1974 |
| Syclenze Limited | Professional & scientific | 2024 |
| Syed by Syed Ltd | Real estate | 2014 |
| Syedalinaqi Ltd | Wholesale & retail | 2023 |
| SYH Group Limited | Wholesale & retail | 2012 |
| Sykes Transport Ltd | Transport & logistics | 2023 |
| Symba Marketing Ltd | Professional & scientific | 2022 |
| Symbiotic.Blue Ltd | Information & communication | 2025 |
| Symilarity Ltd | Information & communication | 2017 |