| Seapower Marine Electronics Limited | Manufacturing | 2008 |
| Seapower Marine Limited | Manufacturing | 2000 |
| Seaquence Ltd | Transport & logistics | 2023 |
| Search Eduhub Limited | Administrative & support | 2025 |
| Sears Construction Ltd. | Construction | 2009 |
| Seasaw Tech Ltd | Wholesale & retail | 2024 |
| Seashore Day Nursery Limited | Extraterritorial | 2001 |
| Seatrade Academy Limited | Professional & scientific | 2013 |
| Seawell Logistics Limited | Transport & logistics | 2025 |
| Sebestyen Ltd | Extraterritorial | 2021 |
| Seby&Cris Building Construction Ltd | Construction | 2019 |
| Secj Investments Limited | Real estate | 2024 |
| Seckford Cottages Limited | Real estate | 2011 |
| Seco Tiacom Ltd | Construction | 2023 |
| Second Meadows Livery Ltd | Agriculture & fishing | 2017 |
| Second Tree Holdings Ltd | Real estate | 2024 |
| Secure Automated Solutions Limited | Administrative & support | 2010 |
| Secure Cctv Ltd | Administrative & support | 2023 |
| Secure Document Storage Limited | Professional & scientific | 2002 |
| Secure Management Solutions Limited | Financial services | 2021 |
| Secure Safecare Ltd | Health & social care | 2025 |
| Securevortex UK Ltd | Extraterritorial | 2026 |
| Securion Consulting Ltd | Information & communication | 2024 |
| Securities Industry Management Association Limited | Other services | 2004 |
| Security Foiling Limited | Manufacturing | 1991 |
| Seden Clarke Limited | Administrative & support | 1978 |
| Sedetransport Ltd | Transport & logistics | 2022 |
| Sedgemore Investments Limited | Extraterritorial | 2011 |
| SEE BEE Property Management Ltd | Real estate | 2023 |
| SEE Cargo UK Limited | Transport & logistics | 2021 |
| Seedready Limited | Information & communication | 2019 |
| Seer Management Services Ltd | Administrative & support | 2025 |
| SEF Rentals Ltd | Real estate | 2025 |
| Sefton Place Ltd | Hospitality | 2025 |
| SEH (Asphalt) Limited | Construction | 1992 |
| SEH (Projects) Limited | Construction | 2003 |
| SEH (Property and Administration) Limited | Professional & scientific | 1971 |
| SEH Commercial Limited | Construction | 2007 |
| SEH French Limited | Construction | 1982 |
| SEH Group Limited | Financial services | 2008 |
| SEH Windows and Doors Limited | Extraterritorial | 2001 |
| Sehbac Limited | Construction | 1985 |
| Seinet-Martin (Holdings) Limited | Financial services | 2008 |
| Seka Trading Limited | Construction | 1994 |
| Sekib Ltd | Professional & scientific | 2018 |
| Selcosemporium Ltd | Wholesale & retail | 2025 |
| Select Icar Limited | Wholesale & retail | 2024 |
| Select Services (EA) Ltd | Transport & logistics | 2014 |
| Selected Recruitment Solutions Ltd | Administrative & support | 2019 |
| Selemea Health Care Ltd | Health & social care | 2015 |
| Self-Help Psychology Limited | Other services | 2024 |
| Seller LOG Limited | Information & communication | 2025 |
| Sellray Ltd | Wholesale & retail | 2025 |
| Selltic Consultancy Ltd | Professional & scientific | 2020 |
| Selviravi Limited | Health & social care | 2014 |
| Semer Secure Storage Limited | Real estate | 2003 |
| Semer Technology Park Limited | Real estate | 2009 |
| Semnite Limited | Information & communication | 2025 |
| Sena Estates Ltd | Real estate | 2025 |
| Sendsory Ltd | Education | 2025 |
| Senel Besim Event Design Limited | Other services | 2016 |
| Senior Salmon Ltd | Administrative & support | 2012 |
| Senselabz Ltd | Professional & scientific | 2025 |
| Senstone EA Limited | Professional & scientific | 2016 |
| Sent Flying Ltd | Professional & scientific | 2016 |
| Sentenelgreen Ltd | Real estate | 2025 |
| Sentenelmaisey Ltd | Real estate | 2025 |
| Sentri Ltd | Administrative & support | 1999 |
| Sentry Farming Ltd | Extraterritorial | 1986 |
| Sentry Farms Limited | Extraterritorial | 1977 |
| Sentry Groundcare Limited | Extraterritorial | 1974 |
| Sentry Limited | Agriculture & fishing | 1999 |
| Sentrynova Ltd | Wholesale & retail | 2025 |
| Senturk Health Consultancy Ltd | Health & social care | 2020 |
| Senzo Group Ltd | Administrative & support | 2025 |
| Septinuary Bidco Limited | Financial services | 2022 |
| Septinuary Midco 1 Limited | Financial services | 2022 |
| Septinuary Midco 2 Limited | Financial services | 2022 |
| Septinuary Topco Limited | Financial services | 2022 |
| Sequrus Ltd | Information & communication | 2025 |
| Serban Transport Ltd | Transport & logistics | 2016 |
| Serbian Express Ltd | Transport & logistics | 2024 |
| Serco IT Management Ltd | Information & communication | 2015 |
| Serderk Logistics Ltd | Transport & logistics | 2025 |
| Sergio Zsolt Transport Ltd | Transport & logistics | 2019 |
| Sergiu Claudiu Nenica Ltd | Construction | 2025 |
| Serious Development Ltd | Administrative & support | 2014 |
| Serious Property Ltd | Real estate | 2015 |
| Servest Aktrion Limited | Financial services | 2018 |
| Service Integrity Limited | Professional & scientific | 1991 |
| Servicedome Ltd | Information & communication | 2025 |
| Services Depan Limited | Professional & scientific | 2025 |
| SET Squared Group Ltd | Professional & scientific | 2018 |
| SET the Bar London Ltd | Professional & scientific | 2016 |
| Setpointhq Ltd | Professional & scientific | 2026 |
| Sevago Ltd | Professional & scientific | 2019 |
| Sevela Tech Ltd | Wholesale & retail | 2022 |
| Seven Alliance Limited | Administrative & support | 2005 |
| Seven Asset Limited | Administrative & support | 1997 |
| Seven Fuel Limited | Extraterritorial | 2009 |