| Smith Bros Heating Ltd | Professional & scientific | 2021 |
| Smith Construction and Design Limited | Construction | 2023 |
| Smith's Environmental Systems Limited | Manufacturing | 2003 |
| SN Contracts Ltd | Construction | 2014 |
| SN GEN Ltd | Information & communication | 2025 |
| SN Orthodontic Limited | Health & social care | 2007 |
| Snackshop Chelmsford Ltd | Wholesale & retail | 2019 |
| Snackvender Ltd | Hospitality | 2026 |
| Snapscope Ltd | Professional & scientific | 2023 |
| Snaz Properties Ltd | Real estate | 2015 |
| Snaz Residential Limited | Real estate | 2019 |
| Snaz Trading Limited | Financial services | 2019 |
| Snhe Holdings Limited | Financial services | 2024 |
| Snicky Snacky Snoo Limited | Hospitality | 2022 |
| SNJ Immigration Advisers Limited | Professional & scientific | 2025 |
| Snowdrop Flat Management Company Limited | Households | 1989 |
| Snows of Great Waltham Limited | Real estate | 1958 |
| Soap Music Ltd | Administrative & support | 2024 |
| Sober Haven C.I.C. | Administrative & support | 2023 |
| Social Work Global Ltd | Health & social care | 2024 |
| Sockdrop UK Limited | Wholesale & retail | 2024 |
| Sofala Partners Ltd | Professional & scientific | 2017 |
| Softcom AM Limited | Professional & scientific | 2025 |
| Softflow (Essex) Limited | Wholesale & retail | 2004 |
| Softops Direct Limited | Wholesale & retail | 2023 |
| SOL Fuel Ltd | Construction | 2022 |
| SOL Grind Ltd | Wholesale & retail | 2025 |
| SOL Strategy Group Ltd | Financial services | 2026 |
| Sola Consulting Services Limited | Professional & scientific | 2023 |
| Sola Solutions Limited | Financial services | 2019 |
| Sola Systems Group Limited | Construction | 2023 |
| Solar Agency AI Ltd | Professional & scientific | 2026 |
| Solar Highways Limited | Financial services | 1999 |
| Solar Synergy UK Ltd | Energy | 2024 |
| Solar-Cleanuk Ltd | Administrative & support | 2025 |
| Solarhome Limited | Construction | 2003 |
| Solarhub Limited | Construction | 2024 |
| Soldbydarren Limited | Real estate | 2025 |
| Sole Plug Limited | Wholesale & retail | 2025 |
| Solent Edge Limited | Real estate | 2016 |
| Solent View Investments Limited | Real estate | 2018 |
| Solid Wood Creations Ltd | Construction | 2021 |
| Solid Worktops Limited | Construction | 2020 |
| Solidarity Ltd | Administrative & support | 2021 |
| Solomon & Stadinsky Limited | Construction | 2019 |
| Solotheone Ltd | Transport & logistics | 2025 |
| Solstice Stories Ltd | Wholesale & retail | 2020 |
| Solus Financial Planning Ltd | Financial services | 2021 |
| Solutions for Outsourcing Limited | Public administration | 2014 |
| Solvix Trade Ltd | Administrative & support | 2025 |
| Soma Verde Therapy Ltd | Health & social care | 2025 |
| Somatic Leadership Co. Limited | Professional & scientific | 2026 |
| Somewheretorent Limited | Real estate | 2024 |
| SON PVT Ltd | Wholesale & retail | 2025 |
| Sonar CMS Ltd | Information & communication | 2020 |
| Sons & John Limited | Transport & logistics | 2021 |
| Soph Cleaning Ltd | Administrative & support | 2025 |
| Sophie's Beauty Parlour Ltd | Health & social care | 2014 |
| Sophius Maximus Limited | Real estate | 2021 |
| Sopwell Real Estate Ltd | Real estate | 2013 |
| Sorplos Limited | Information & communication | 2025 |
| Sorrel Project Services Limited | Administrative & support | 2016 |
| Soul Productions Limited | Information & communication | 2013 |
| Soul Street Productions Ltd | Arts & recreation | 2017 |
| Sound Kitchen Market Place Enterprise Ltd | Manufacturing | 2025 |
| Soundfield Limited | Extraterritorial | 2020 |
| Source IT Here Ltd | Wholesale & retail | 2025 |
| Source Supplements Ltd | Wholesale & retail | 2025 |
| South & East Grape Harvesting Ltd | Agriculture & fishing | 2022 |
| South East Maintenance Group Ltd | Households | 2021 |
| South East Plant & Tool Hire Ltd | Administrative & support | 2024 |
| South Eastern Pipelines Limited | Extraterritorial | 2015 |
| South Island Development Limited | Construction | 2018 |
| South Woodam Barbers Ltd | Other services | 2019 |
| South Woodham Ferrers Bowls Club CIC | Arts & recreation | 2022 |
| South Woodham Plastering Ltd | Construction | 2024 |
| South Woodham Private Hire Limited | Transport & logistics | 1997 |
| Southchurch Solutions Limited | Professional & scientific | 2005 |
| Southecom Ltd | Information & communication | 1999 |
| Southend Airport Car Parking Ltd | Administrative & support | 2014 |
| Southend Auto Electrics Limited | Wholesale & retail | 2003 |
| Southend Jazz Festival CIC | Arts & recreation | 2022 |
| Southend Oral Surgery UK Limited | Health & social care | 2021 |
| Southend Outdoor Cinema Ltd | Other services | 2015 |
| Southern (UK) Transmissions Limited | Wholesale & retail | 1999 |
| Southern Contract Services Limited | Construction | 2002 |
| Southern Counties Limited | Construction | 2014 |
| Southern Counties Roofing Contractors Limited | Construction | 1987 |
| Southern Counties Roofing Holdings Limited | Administrative & support | 2013 |
| Southern Counties Roofing Limited | Extraterritorial | 2015 |
| Southern Land and Acquisitions Limited | Real estate | 2023 |
| Southern Reclaim Ltd | Wholesale & retail | 1980 |
| Southern Star Coaches Limited | Transport & logistics | 1974 |
| Southminster Hall Events Ltd | Hospitality | 2021 |
| Southweald Computers Limited | | 1987 |
| Sovereign Court (Rayleigh) Management Limited | Households | 2011 |
| SP Holidays Ltd | Administrative & support | 2021 |
| Spacd Properties Ltd | Real estate | 2021 |
| Spacio Ltd. | Construction | 2009 |
| Span Global Ltd | Real estate | 2021 |