| Sonic Funding Capital 3 Limited | Financial services | 2026 |
| Sonic Funding Partners Limited | Financial services | 2020 |
| Sonning Capital Limited | Financial services | 2017 |
| Sonroc Solutions Ltd | Construction | 2020 |
| Sony Pijjana Ltd | Construction | 2025 |
| Soonmove Ltd | Real estate | 2025 |
| Sopebi Ventures Ltd | Administrative & support | 2018 |
| Sophie.Tank Ltd | Real estate | 2018 |
| Sorensen Consulting Ltd | Professional & scientific | 2020 |
| SOS Osteopath Limited | Health & social care | 2022 |
| Souie Electrical Limited | Construction | 2024 |
| Soulve Ltd | Professional & scientific | 2025 |
| Sound Financial Planning Group Ltd | Professional & scientific | 2004 |
| Sound Financial Planning Limited | Financial services | 2000 |
| Sound Financial Services LLP | | 2004 |
| South East Asbestos Surveys Ltd | Water & waste | 2014 |
| South East Camper Conversions Ltd | Manufacturing | 2019 |
| South East Cooling Limited | Construction | 1991 |
| South East Drawing Office Limited | Wholesale & retail | 2005 |
| South East Labour Limited | Administrative & support | 2024 |
| South East London Mechanical Services Ltd | Professional & scientific | 2025 |
| South East Renovations Ltd | Construction | 2020 |
| South Essex Building Solutions Ltd | Construction | 2021 |
| South Essex Gymnastics Club Limited | Arts & recreation | 2009 |
| South Essex Lactation Support CIC | Health & social care | 2019 |
| South West London Design&Build Limited | Construction | 2016 |
| Southby Properties Ltd | Real estate | 2026 |
| Southchurch Pointe Limited | Construction | 2024 |
| Southchurch Pointe Management Company Ltd | Households | 2025 |
| Southchurch Road Properties Limited | Real estate | 1963 |
| Southcliff Court Consultancy Ltd | Financial services | 2015 |
| Southeast Essex Plastering Limited | Construction | 2016 |
| Southend Coastal Surgeries Limited | Health & social care | 2024 |
| Southend Community Events CIC | Administrative & support | 2017 |
| Southend Drinks Limited | Wholesale & retail | 2021 |
| Southend East PCN Limited | Health & social care | 2023 |
| Southend Flying Club Limited | Professional & scientific | 2001 |
| Southend Flying School Limited | Professional & scientific | 2001 |
| Southend School of Flying Limited | Professional & scientific | 2001 |
| Southern Aroma Ltd | Hospitality | 2025 |
| Southern Civils and Utilities Limited | Construction | 2021 |
| Southern Civils Property Development Services Limited | Real estate | 2026 |
| Southern Commercial Heating Ltd | Construction | 2019 |
| Southern Render Solutions Ltd | Construction | 2018 |
| Southstars Management Limited | Arts & recreation | 2024 |
| Southway Asbestos Limited | Water & waste | 2019 |
| Souvlaki Kingdom Ltd | Hospitality | 2025 |
| Sovereign (Southend) Limited | Real estate | 2002 |
| Sovereign Alliance Limited | Construction | 1997 |
| Sovereign House Properties Limited | Real estate | 1998 |
| Sovereign Traditional Builders Limited | Construction | 2024 |
| SP Investment Property Group Ltd | Real estate | 2026 |
| SP Joint Ventures Ltd | Real estate | 2024 |
| SP Signs and Design Limited | Administrative & support | 2018 |
| Spaceology Limited | Professional & scientific | 2014 |
| Spare Time Activities Ltd. | Wholesale & retail | 2019 |
| Spare UP Ltd | Wholesale & retail | 2025 |
| Spargoland | Other services | 2015 |
| Sparkle and Shine Knightsbridge Limited | Administrative & support | 2025 |
| Sparkling Bins Ltd | Administrative & support | 2020 |
| Sparks Laser Services Limited | Manufacturing | 2001 |
| Sparksphere IT Ltd | Information & communication | 2024 |
| Sparky ROK Limited | Construction | 2023 |
| Sparrow Innovations Limited | Professional & scientific | 2025 |
| Sparx Electrical Limited | Construction | 2024 |
| SPB Building Services Ltd | Construction | 2015 |
| SPB Technologies Ltd | Information & communication | 2014 |
| Spcp Holdings Limited | Professional & scientific | 2021 |
| Spec Training Ltd | Education | 2019 |
| Special Metals Fabrication Limited | Professional & scientific | 2014 |
| Specialised Spraying Services Ltd | Construction | 2018 |
| Specialist Coating Wholesales Ltd | Manufacturing | 2018 |
| Specialist Ductwork Solutions Limited | Construction | 2017 |
| Specialist Medical Transport Ltd | Transport & logistics | 2018 |
| Specialist Procurement Consultancy Services Limited | Professional & scientific | 2005 |
| Spectra Analysis Services Limited | Professional & scientific | 2003 |
| Spectra Contracts Limited | Construction | 2023 |
| Spectra Demolition Limited | Extraterritorial | 2023 |
| Spectra DMT Limited | Water & waste | 2025 |
| Spectrum World Ltd | Wholesale & retail | 2014 |
| Speedhouse Studio Ltd | Professional & scientific | 2026 |
| Speedra Limited | Transport & logistics | 2025 |
| Speedrite International Ltd. | Manufacturing | 1994 |
| Spencer B Properties Ltd | Real estate | 2025 |
| Spencer Properties LLC Ltd | Real estate | 2026 |
| Spencer’S Cosmetics Limited | Wholesale & retail | 2025 |
| Spicy Curry (Basildon) Ltd | Hospitality | 2023 |
| Spin Your Web Ltd | Wholesale & retail | 2023 |
| Spiral Security Limited | Construction | 1997 |
| Spires (UK) Limited | Administrative & support | 2002 |
| Spirit Pure Creativity Limited | Manufacturing | 2009 |
| Spirit Vision Limited | Hospitality | 2005 |
| Splender Care Limited | Public administration | 2023 |
| SPM Trading Services Ltd | Professional & scientific | 2023 |
| Spoon Buffet Ltd | Hospitality | 2022 |
| Sport-Savvy Ltd | Education | 2024 |
| Sportadam Ltd | Financial services | 2007 |
| Spotlight Living Ltd | Real estate | 2025 |
| Spouting Horn Limited | Real estate | 2021 |
| Spraying 4 YOU Ltd | Construction | 2018 |