| Serenitehauscollective Limited | Households | 2025 |
| Serenity Cleaning Team Ltd | Administrative & support | 2024 |
| Serenity Spa Limited | Other services | 2018 |
| Seronam Ltd | Information & communication | 2014 |
| Serv Investments Ltd | Real estate | 2018 |
| Services and Logistics LLP | | 2022 |
| Sesom Ltd | Professional & scientific | 2018 |
| SET the Trend Limited | Administrative & support | 2015 |
| Seth Automotive UK Ltd | Professional & scientific | 2011 |
| Sette Bello SM Ltd | Professional & scientific | 2024 |
| Seturaworks Ltd | Administrative & support | 2025 |
| Seva Optics Ltd | Health & social care | 2016 |
| Sevac Limited | Energy | 2003 |
| Seven Arches Investments Limited | Real estate | 2018 |
| Sewells Fuels Ltd | Water & waste | 2023 |
| Sexi Property Group Ltd | Real estate | 2016 |
| SF Clothing Ltd | Wholesale & retail | 2012 |
| SF Holdings Group Limited | Financial services | 2024 |
| Sfqr Limited | Construction | 2019 |
| SG Mortgage Consultants Limited | Financial services | 2015 |
| SG Voyce Limited | Administrative & support | 2019 |
| SGB Fire & Security Limited | Construction | 2018 |
| SGL and SON Scaffolding Ltd | Construction | 2016 |
| SGR Estates Ltd | Real estate | 2017 |
| SH Brands Group Ltd | Wholesale & retail | 2022 |
| Shadow Property Development & Management Services Limited | Real estate | 2018 |
| Shadow Track Ltd | Information & communication | 2026 |
| Shakespeare House (Dedham) Properties Limited | Construction | 1991 |
| Shakir & Roberts Ltd | Wholesale & retail | 2024 |
| Shakir Enterprises Ltd | Wholesale & retail | 2024 |
| Shana KAD Coaching Ltd | Professional & scientific | 2020 |
| Shannon Watson Ltd | Administrative & support | 2024 |
| Shanthy Properties Limited | Real estate | 2024 |
| Sharif Capital Limited | Real estate | 2025 |
| Sharif Estates Limited | Administrative & support | 2014 |
| Sharp & Bentley Ltd | Professional & scientific | 2013 |
| Sharp's Electrical Services Ltd | Construction | 2026 |
| Sharu Kumar Boxing and Fitness Limited | Health & social care | 2025 |
| Shaun Smith Events Ltd | Hospitality | 2021 |
| Shawbrook Bank Limited | Financial services | 1944 |
| Shawbrook Group PLC | Professional & scientific | 2010 |
| Shea Limited | Households | 2025 |
| Shebang Digital Limited | Professional & scientific | 2017 |
| Sheehan Management Ltd. | Administrative & support | 2016 |
| Sheezal Hub Ltd | Information & communication | 2025 |
| Shek Limited | Administrative & support | 2012 |
| Shell and Beyond Projects Limited | Professional & scientific | 2009 |
| Shenfield Advisory Services Ltd | Professional & scientific | 2018 |
| Shenfield Bakery & Sandwich Bar Ltd | Hospitality | 2011 |
| Shenfield Barber Limited | Other services | 2016 |
| Shenfield Dental Care Limited | Health & social care | 2022 |
| Shenfield High School | Education | 2012 |
| Shenfield Management Company Limited | Hospitality | 2011 |
| Shenfield Properties Limited | Construction | 2004 |
| Shepherd Motors Ltd | Wholesale & retail | 2017 |
| Shepperds TYE Management Company Limited | Households | 2009 |
| Sherbourne Groundworks Ltd | Construction | 2019 |
| Sherlock Holmes Group Limited | Real estate | 2026 |
| Shiners Property Services Ltd | Other services | 1999 |
| Shining M&G Ltd | Administrative & support | 2024 |
| Shogun Medical Limited | Manufacturing | 2025 |
| Shout Contractors Ltd | Construction | 2022 |
| Shree Krishna Convenience Store Limited | Wholesale & retail | 2026 |
| Shri Krishna Wholesale Limited | Wholesale & retail | 2025 |
| SIA Wellbeing Ltd | Wholesale & retail | 2025 |
| Siam Thai Therapy Ltd | Other services | 2021 |
| Siblings & Sons Ltd | Real estate | 2020 |
| Side Extension Limited | Construction | 2016 |
| Sideline Design Limited | Manufacturing | 2000 |
| Sideline Design Trustee Limited | Extraterritorial | 2024 |
| Sidrae Ltd | Construction | 2022 |
| Siger Salons Limited | Other services | 2023 |
| Signal Park LLP | | 2023 |
| Signature Contracts Ltd | Construction | 2023 |
| Signature Electrics Ltd | Construction | 2021 |
| SIJ Property Developments Ltd | Real estate | 2026 |
| Sijilmasa Ltd | Wholesale & retail | 2019 |
| Silver OWL Investments Ltd | Real estate | 2020 |
| Silver Service Estate Agents Limited | Administrative & support | 1993 |
| Silver Star Medical Education Limited | Professional & scientific | 2017 |
| Silverbush Limited | Construction | 1993 |
| Silverleaf Leisure Ltd | Hospitality | 2023 |
| Silverpatch Properties Ltd | Real estate | 2018 |
| Silvershear Limited | Real estate | 2021 |
| Silverwave Developments Brentwood Limited | Real estate | 2026 |
| Silverwave Developments Limited | Real estate | 2026 |
| SIM67 Ltd | Real estate | 2026 |
| Simjay Properties Ltd | Real estate | 2018 |
| Simon Barker Consulting Ltd | Professional & scientific | 2009 |
| Simon Khan Foundation | Arts & recreation | 2012 |
| Simon Leigh Associates Limited | Construction | 2006 |
| Simple Gospel Ministries | Other services | 2018 |
| Simple Sourcing Limited | Wholesale & retail | 2011 |
| Simplecloud Consulting Ltd | Information & communication | 2022 |
| Simplicity Solutions Ltd | Other services | 2016 |
| Simplus Transformation Ltd | Information & communication | 2017 |
| Simplxa Holdings Ltd | Financial services | 2025 |
| Simplxa Technologies Ltd | Information & communication | 2025 |
| Simplxit Ltd | Wholesale & retail | 2023 |
| Simply Fascia Limited | Construction | 2015 |