| Sea Spirit & Stones Limited | Other services | 2025 |
| Seagate Estates Ltd | Construction | 2022 |
| Seanchai Ltd | Arts & recreation | 2020 |
| Seaside Pizza Limited | Hospitality | 2023 |
| Seaside Romeo Limited | Professional & scientific | 2024 |
| SEB G Driving School Ltd | Education | 2026 |
| Sebastian Keep Ltd | Information & communication | 2020 |
| Secnuvo Ltd | Information & communication | 2024 |
| Secol Engineering Limited | Manufacturing | 1979 |
| Securities Research Associates Ltd | Administrative & support | 2001 |
| Sedlescombe Gardens Residents Association Limited | Real estate | 1997 |
| Sedlescombe Property Ltd | Real estate | 2021 |
| Seefood Immersive Ltd | Information & communication | 2019 |
| Sefta Limited | Professional & scientific | 1984 |
| Seldibarber Ltd | Other services | 2025 |
| Select Accountancy Services Limited | Professional & scientific | 2017 |
| Sellens French LLP | | 2012 |
| Senex Medical Ltd | Manufacturing | 2025 |
| Seniors Helping Seniors (Thames Valley) Ltd | Other services | 2021 |
| Senlac Windows Limited | Manufacturing | 2025 |
| Sentry Interactive Ltd | Professional & scientific | 2015 |
| Seol + Gold Limited | Wholesale & retail | 2020 |
| Sepia Hastings Limited | Hospitality | 2022 |
| Sevensedge Ltd | Professional & scientific | 2019 |
| Sewell Assets LLP | | 2011 |
| SG Takeaway Food Ltd | Hospitality | 2025 |
| Sham 69 Limited | Information & communication | 2012 |
| Shield-Maiden Security Service Ltd | Administrative & support | 2026 |
| Shish Hastings Ltd | Hospitality | 2026 |
| Shopforu Ltd | Transport & logistics | 2020 |
| Sichuan Weige Technology Co Ltd | Information & communication | 2025 |
| Sidney House Residents Association Limited | Extraterritorial | 1989 |
| Silver BEE Consulting Limited | Professional & scientific | 2024 |
| Silver Hill Property Ltd. | Real estate | 2021 |
| Silver Homes (Crowborough) Ltd | Construction | 2026 |
| Silver Homes Contracting (South East) Ltd | Construction | 2024 |
| Silver Homes Contracting Ltd | Households | 2020 |
| Silver Homes Projects Ltd | Construction | 2023 |
| Silver Plant Hire LLP | | 2024 |
| Silverlight Property Services Ltd | Manufacturing | 2018 |
| Silvester Norton LLP | | 2018 |
| Simore Ltd | Wholesale & retail | 2025 |
| Simply Solutions Consultancy Ltd | Administrative & support | 2017 |
| Sinay Logistics Limited | Wholesale & retail | 2024 |
| SIR Skunk Limited | Wholesale & retail | 2023 |
| Sister Developments Limited | Construction | 2018 |
| Site Project Solutions Limited | Professional & scientific | 2012 |
| Site Remediation Limited | Construction | 2009 |
| SJ Greenwich Holdings Ltd | Financial services | 2025 |
| SJW Rendering Ltd | Construction | 2020 |
| Skills & Learning in the Community Ltd | Education | 2007 |
| Skimking Construction Ltd | Extraterritorial | 2023 |
| Skinworks Aesthetics Limited | Other services | 2020 |
| Skyline Design Limited | Professional & scientific | 2003 |
| SLA Property Solutions Ltd | Real estate | 2020 |
| Slre Properties Limited | Real estate | 2017 |
| Small Machine Software Limited | Information & communication | 2024 |
| Small Web Solutions Ltd | Extraterritorial | 2024 |
| Small World Consultancies Ltd | Health & social care | 2011 |
| Smart Care With Stella Ltd | Health & social care | 2023 |
| Smart Electrical Connections Ltd | Information & communication | 2016 |
| Smart Electronic Solutions Ltd | Manufacturing | 2014 |
| Smarter Transmissions Limited | Wholesale & retail | 2025 |
| Smat Accountancy Limited | Professional & scientific | 2015 |
| Smileology Practice Ltd | Health & social care | 2026 |
| Smiles Building Company Ltd | Construction | 2021 |
| Smooth Start Driving School Ltd | Education | 2024 |
| Sniff and Spit Limited | Hospitality | 2003 |
| Soak Store Limited | Wholesale & retail | 2009 |
| Social Broadcasts Ltd | Professional & scientific | 2012 |
| Social Education Limited | Education | 2019 |
| Soft Glow Ltd | Other services | 2025 |
| SOL Cafe C.I.C. | Health & social care | 2020 |
| SOL Ecosystem Ltd | Information & communication | 2012 |
| SOL R Flare Ltd | Administrative & support | 2010 |
| Solgen Solutions Limited | Construction | 2025 |
| Solution Distribution Limited | Information & communication | 2014 |
| Solution Focused Psychotherapy & Training Services Limited | Health & social care | 2021 |
| Soma Fmcg Ltd | Wholesale & retail | 2022 |
| Sonics Collective CIC | Arts & recreation | 2025 |
| Sonixinema Ltd | Information & communication | 2017 |
| Soparfi Distribution Ltd | Administrative & support | 2019 |
| Sound Society CIC | Education | 2019 |
| Soundcastle Ltd | Arts & recreation | 2012 |
| Sourbandesign Limited | Construction | 2008 |
| South Coast Homes East Sussex Ltd | Real estate | 2020 |
| South Coast Keys Ltd | Wholesale & retail | 2023 |
| South Coast Metalworks Limited | Manufacturing | 2009 |
| South Coast Restaurant Services LLP | | 2008 |
| South East Creatives Ltd | Arts & recreation | 2019 |
| South View Court/ Leeds Close Maintenance Limited | Real estate | 2017 |
| South Westerly Winds Limited | Professional & scientific | 2021 |
| SOUTH1 Developments Limited | Real estate | 2016 |
| Southeast Care Health Ltd | Administrative & support | 2016 |
| Southern Valve and Fitting Co. Limited(The) | Wholesale & retail | 1981 |
| Southview Court (Five) RTM Company Limited | Households | 2020 |
| Southview Court (Four) RTM Company Limited | Households | 2020 |
| Southview Court (One) RTM Company Limited | Households | 2020 |
| Southview Court (Three) RTM Company Limited | Households | 2020 |
| Southview Court (Two) RTM Company Limited | Households | 2021 |