| Selfab Trans Ltd | Transport & logistics | 2026 |
| Selibiks Ltd | Information & communication | 2025 |
| Selisa Property Investments Ltd | Real estate | 2024 |
| Seller Aura Ltd | Wholesale & retail | 2025 |
| Sellina Care Limited | Health & social care | 2019 |
| Selocore Ltd | Information & communication | 2025 |
| Selva(Pvt) Limited | Wholesale & retail | 2025 |
| Selvemotor Group Limited | Administrative & support | 2025 |
| Semaphore Services Limited | Construction | 2022 |
| Senaptix Limited | Information & communication | 2025 |
| Senator Luton Limited | Households | 1987 |
| Senec Ltd | Professional & scientific | 2020 |
| Seniah Limited | Professional & scientific | 2023 |
| Seniur Properties Limited | Real estate | 2024 |
| SENSORY5 Ltd | Health & social care | 2025 |
| Sentinel Security Guarding Services Ltd | Administrative & support | 2023 |
| Sentinel Training Solutions Ltd | Education | 2024 |
| Sentra One Ltd | Administrative & support | 2025 |
| Sentria Limited | Administrative & support | 2025 |
| Sentrixa Ltd | Professional & scientific | 2026 |
| Sentry Fire Protection Limited | Public administration | 2023 |
| Seny Ltd | Transport & logistics | 2016 |
| Seolva Limited | Wholesale & retail | 2025 |
| Seprofix Ltd | Administrative & support | 2026 |
| Serac Services Limited | Professional & scientific | 2022 |
| Serano Living CIC | Hospitality | 2026 |
| Serar Car Ltd | Transport & logistics | 2019 |
| Serban Build Limited | Construction | 2025 |
| SERBAN87 Limited | Transport & logistics | 2017 |
| Serendipity&Az Ltd | Wholesale & retail | 2025 |
| Serene Seasons Care Ltd | Health & social care | 2024 |
| Serene Solutions Limited | Information & communication | 2009 |
| Serene Steps Nursery Ltd | Health & social care | 2025 |
| Serene Youth Care Homes Ltd | Hospitality | 2024 |
| Serenease Limited | Education | 2025 |
| Serenityglowuk Limited | Other services | 2025 |
| Sergiu Suman Ltd | Wholesale & retail | 2026 |
| Seriesx Systems Ltd | Information & communication | 2025 |
| Serin Holdings Limited | Real estate | 2023 |
| Servaga Ltd | Wholesale & retail | 2021 |
| Service 4U Limited | Transport & logistics | 2012 |
| Service Apartments Limited | Real estate | 2021 |
| Servicedesk Limited | Information & communication | 2007 |
| Services by Vlad Ltd | Administrative & support | 2022 |
| Services Consultants Limited | Transport & logistics | 2024 |
| Services MA Limited | Wholesale & retail | 2021 |
| Services RJ Limited | Manufacturing | 2020 |
| SERVICESJDD3 Ltd | Wholesale & retail | 2025 |
| Servicesjddcleaning Ltd | Administrative & support | 2025 |
| Setonsey Care Services Ltd | Public administration | 2023 |
| Sett's Services Ltd | Professional & scientific | 2017 |
| Settled Waters Childrens Services Ltd | Education | 2026 |
| Sevdican Ltd | Financial services | 2025 |
| Seven Bros Cookware Ltd | Wholesale & retail | 2014 |
| Seven Healthcare Ltd | Health & social care | 2024 |
| Seven Kings Construction Limited | Construction | 2014 |
| Seven Kings Developments Limited | Financial services | 2017 |
| Seven Kings Investments Limited | Financial services | 2017 |
| Seven Kings Property Limited | Construction | 2017 |
| Seven Kings Property Management Limited | Real estate | 2010 |
| Seven Star Construction Luton Limited | Construction | 2024 |
| Seven Star Finance Limited | Financial services | 2002 |
| Seven Star Properties Limited | Real estate | 2004 |
| Seven UP Logistic Ltd | Transport & logistics | 2023 |
| Several Seats C.I.C. | Health & social care | 2021 |
| Sevidar Limited | Wholesale & retail | 2003 |
| Sewell Manor Limited | Construction | 2018 |
| Sewell Manor Management Company Limited | Households | 2019 |
| Sexplained Foundation | Health & social care | 2001 |
| Sexplained Limited | Administrative & support | 1999 |
| Seymour Stores Ltd | Wholesale & retail | 2018 |
| SF Build Ltd | Construction | 2025 |
| SFC & Pizza Direct Limited | Wholesale & retail | 2016 |
| SFC Peri Peri Ltd | Hospitality | 2016 |
| SFI Pharma Ltd | Health & social care | 2022 |
| Sfx-Mechs Limited | Arts & recreation | 2014 |
| SFZ Financial Services Ltd | Professional & scientific | 2018 |
| SG Business Analytics Ltd | Professional & scientific | 2019 |
| SG Cleaning and Maintenance Services Ltd | Administrative & support | 2026 |
| SG Electrical Install and Services Ltd | Construction | 2018 |
| SG Intercontinental Ltd | Wholesale & retail | 2024 |
| SG Supplies Limited | Manufacturing | 2017 |
| SGC Groundworks Ltd | Construction | 2025 |
| SGC Martial Arts Ltd | Arts & recreation | 2017 |
| Sgcash Ltd | Wholesale & retail | 2026 |
| SGJ7 Ltd | Wholesale & retail | 2025 |
| Sgkp Investments Limited | Real estate | 2017 |
| Sgkp Properties Ltd | Real estate | 2026 |
| SGM Home Renovation Ltd | Construction | 2024 |
| SGM Stags Ltd | Construction | 2011 |
| Sgmr Ltd | Extraterritorial | 2022 |
| SGR Chauffeurs Ltd | Transport & logistics | 2025 |
| SGS Scaffolding Ltd | Construction | 2015 |
| SH Easypick Ltd | Wholesale & retail | 2025 |
| SH Executive Travel Ltd | Transport & logistics | 2024 |
| SH Investment Properties Limited | Real estate | 2024 |
| SH UK Management Ltd | Financial services | 2021 |
| Sh&E Legacy Developments Limited | Real estate | 2026 |
| SH14ADS Pharma Ltd | Professional & scientific | 2019 |
| SHA Global Trading UK Limited | Wholesale & retail | 2021 |