| Serinexsecure Limited | Information & communication | 2025 |
| Serinity Healthkare Ltd | Health & social care | 2025 |
| Serious Interiors Limited | Construction | 2017 |
| Serious Schnitzel Limited | Hospitality | 2023 |
| Sero Consulting Limited | Professional & scientific | 2003 |
| Sero Fires Limited | Wholesale & retail | 2025 |
| Serotonin Scrolling Limited | Information & communication | 2024 |
| Serova Limited | Administrative & support | 2025 |
| Serripio Investments (UK) Limited | Professional & scientific | 2005 |
| Serve Afghanistan | Extraterritorial | 2003 |
| Server Edge Group Ltd | Wholesale & retail | 2025 |
| Server Health Limited | Information & communication | 2007 |
| Serversure Limited | Information & communication | 1990 |
| Servicar Ltd | Wholesale & retail | 2026 |
| SERVICE4EDUCATION Limited | Education | 2017 |
| Servicehub Limited | Extraterritorial | 2015 |
| Services Design Associates Limited | Professional & scientific | 1988 |
| Servologic Control Ltd | Manufacturing | 2024 |
| SET Point Management Limited | Administrative & support | 2024 |
| SET Square Studio Ltd | Professional & scientific | 2019 |
| Seth Moran Ltd | Education | 2022 |
| Setho UK Limited | Health & social care | 2014 |
| Setl Management Company Limited | Households | 2023 |
| Seven Boys Limited | Hospitality | 2025 |
| Seven Creative Limited | Professional & scientific | 2005 |
| Seven Electrical Solutions Limited | Construction | 2022 |
| Seven Hill Spice Ltd | Hospitality | 2018 |
| Seven Hill Tyres Limited | Wholesale & retail | 2016 |
| Seven Hills Accountants Limited | Professional & scientific | 2022 |
| Seven Hills Building & Construction Ltd | Construction | 2023 |
| Seven Hills Civils Limited | Construction | 2020 |
| Seven Hills Cleaning Ltd | Administrative & support | 2020 |
| Seven Hills Crafts Limited | Wholesale & retail | 2015 |
| Seven Hills Creative Limited | Professional & scientific | 2018 |
| Seven Hills Design Limited | Professional & scientific | 2022 |
| Seven Hills Energy Ltd | Manufacturing | 2025 |
| Seven Hills Engineering Limited | Professional & scientific | 2018 |
| Seven Hills English Limited | Administrative & support | 2014 |
| Seven Hills Fabrication Limited | Professional & scientific | 2018 |
| Seven Hills Homecare Limited | Health & social care | 2021 |
| Seven Hills Motorhome Hire Ltd | Administrative & support | 2026 |
| Seven Hills Optical Limited | Health & social care | 2011 |
| Seven Hills Outdoors Limited | Education | 2023 |
| Seven Hills Plant Ltd | Construction | 2026 |
| Seven Hills Psychology Ltd | Health & social care | 2023 |
| Seven Hills QS Ltd | Professional & scientific | 2023 |
| Seven Hills Solar Ltd | Construction | 2024 |
| Seven Hills Stud Ltd | Agriculture & fishing | 2023 |
| Seven Hills Transport Services Ltd | Transport & logistics | 2019 |
| Seven Hills Tree Services Ltd | Administrative & support | 2026 |
| Seven Hills Tyres Limited | Water & waste | 2025 |
| Seven Knights Limited | Construction | 2025 |
| Seven Peaks Properties Ltd | Hospitality | 2009 |
| Seven Points Trading Limited | Professional & scientific | 2015 |
| Seven Property Lettings Ltd | Real estate | 2020 |
| Seven Scapes Garden Services Ltd | Administrative & support | 2026 |
| Seven Seas Fish Bar Limited | Hospitality | 2024 |
| Seven Sisters Sports Ltd | Wholesale & retail | 2018 |
| Seven Steps Support Ltd | Health & social care | 2013 |
| Seven Sycamores Ltd | Real estate | 2020 |
| Seven Virtues Ltd | Information & communication | 2017 |
| Seven White Pixels Limited | Information & communication | 2017 |
| Sevenairs Consulting Limited | Professional & scientific | 2017 |
| Sevenhills Electrical Services Limited | Construction | 2026 |
| Sevenhills Estates Limited | Construction | 1991 |
| Sevenhills Investment Holdings Ltd | Real estate | 2022 |
| Sevenhills Land and Homes Ltd | Construction | 2020 |
| Sevenhills Reclamation Ltd | Wholesale & retail | 2021 |
| Sevensix Digital Limited | Information & communication | 2014 |
| Sevenstar (Yorkshire) Ltd | Manufacturing | 2026 |
| Sevenstonesproperty Ltd | Real estate | 2022 |
| Seventeen Seconds Ltd. | Education | 2022 |
| Sewell Wallis HR Limited | Administrative & support | 2020 |
| Sewell Wallis Recruitment Limited | Administrative & support | 2020 |
| Sewer Solutions Limited | Water & waste | 2014 |
| Sewercare Limited | Professional & scientific | 2025 |
| Sexy Hair Limited | Other services | 2008 |
| Seyed a 2 Z Ltd | Transport & logistics | 2022 |
| Seymour & Lerhn Limited | Information & communication | 2021 |
| Seyon ROW Ltd | Wholesale & retail | 2026 |
| Sezatoarea C.I.C. | Education | 2025 |
| SF Builders Ltd | Administrative & support | 2017 |
| SF Ortho Limited | Health & social care | 2024 |
| SF Sonography Ltd | Health & social care | 2025 |
| SFC Flavours Limited | Hospitality | 2024 |
| SFD Catering Ltd | Hospitality | 2009 |
| SFD Core Projects Ltd | Professional & scientific | 2026 |
| Sfixx Limited | Manufacturing | 2017 |
| SFK Law Limited | Extraterritorial | 2019 |
| SFK Optical Ltd | Health & social care | 2024 |
| Sfpubs Ltd | Hospitality | 2025 |
| SFS Building Ltd | Construction | 2020 |
| Sfven Ltd | Information & communication | 2020 |
| SFW Communications Ltd | Information & communication | 2015 |
| SG Berkshire Ltd | Financial services | 2012 |
| SG Chairs Limited | Other services | 2025 |
| SG Fire Systems Ltd | Administrative & support | 2017 |
| SG Investment Properties Limited | Real estate | 2025 |
| SG Mortgage Hub Ltd | Financial services | 2023 |
| SG Property Agents Limited | Real estate | 2008 |