| Silverlight Counselling Ltd | Health & social care | 2021 |
| Simian Saboteur Ltd | Wholesale & retail | 2023 |
| Simon Moore Ltd | Professional & scientific | 2024 |
| Simplistique Limited | Other services | 2023 |
| Simply Carpentry Limited | Construction | 2013 |
| Sirayo Limited | Manufacturing | 2021 |
| Sisters With Sparkle Ltd | Other services | 2023 |
| SIX a Side Football Ltd | Arts & recreation | 2018 |
| SJ Mitchell Investments Ltd | Financial services | 2023 |
| Sjja Signalling Ltd | Transport & logistics | 2023 |
| SJR Farming Limited | Agriculture & fishing | 2006 |
| SJT Medical Limited | Administrative & support | 2005 |
| Sjtc Group Ltd | Administrative & support | 2017 |
| SK Building & Electrical Ltd | Construction | 2022 |
| SK CAD Services Limited | Administrative & support | 2009 |
| Skee-Tex Limited | Wholesale & retail | 1952 |
| Skin 44 Ltd | Other services | 2024 |
| Skip-Pro Limited | Administrative & support | 2017 |
| Skmb Ecom Limited | Wholesale & retail | 2024 |
| Skolf Ltd | Construction | 2026 |
| Skott Consulting Ltd | Administrative & support | 2016 |
| Sky Fencing Ltd | Wholesale & retail | 2023 |
| Sky Proof Roofing Ltd | Construction | 2025 |
| Skyhunt Ltd | Administrative & support | 2020 |
| Skylight Property Ventures Ltd | Real estate | 2021 |
| Skynet Commerce Limited | Administrative & support | 2018 |
| Skynet Systems Ltd | Information & communication | 2025 |
| Skytech Talent Ltd | Administrative & support | 2025 |
| SL Architectural Limited | Professional & scientific | 2013 |
| Slip Back in Time Ltd | Arts & recreation | 2018 |
| Slipped Discs Brown Sugar Limited | Hospitality | 2016 |
| Slnets Ltd | Information & communication | 2025 |
| SLP Holdings Ltd | Financial services | 2020 |
| SM Property Refurb Ltd | Construction | 2025 |
| Smart Coatings Ltd | Construction | 2016 |
| Smart Planning Limited | Professional & scientific | 2002 |
| Smartbuy With US Ltd | Wholesale & retail | 2024 |
| Smarter Air Solutions Ltd | Energy | 2025 |
| SME Estates Ltd | Real estate | 2019 |
| SMG Interiors Limited | Construction | 2014 |
| Smilers Holiday Lets Ltd | Real estate | 2022 |
| Smiles Engineering Ltd | Administrative & support | 2021 |
| Smith AJ Ltd | Other services | 2016 |
| Smith Lachter Limited | Real estate | 2003 |
| Smith Storage (Holdings) Limited | Real estate | 2007 |
| Smith Storage Limited | Transport & logistics | 2025 |
| Smoovhead Ltd | Wholesale & retail | 2025 |
| Snap CAB Ltd | Transport & logistics | 2026 |
| Snaretree Limited | Real estate | 1979 |
| Snowpoint Digital Ltd | Information & communication | 2026 |
| SO & Co London Limited | Professional & scientific | 2025 |
| SO Many Legs Ltd | Wholesale & retail | 2017 |
| SO Scents Ltd | Wholesale & retail | 2020 |
| Social Care Initiatives Limited | Health & social care | 2013 |
| Social Land Limited | Professional & scientific | 2021 |
| SOF Installation and Testing Services Ltd | Construction | 2015 |
| Soho Spirit Limited | Wholesale & retail | 2013 |
| SOL Sports Coaching Ltd | Arts & recreation | 2025 |
| Solar Energy South Limited | Construction | 2025 |
| Solariseleven Limited | Information & communication | 2023 |
| Solid Landscaping & Fencing Ltd | Administrative & support | 2026 |
| Solitair Services Limited | Professional & scientific | 1999 |
| Solomon Marketing Ltd | Administrative & support | 2017 |
| Solstice Beta Management Company Limited | Professional & scientific | 2003 |
| Solving IT Limited | Information & communication | 1998 |
| SOM Holdings Ltd | Real estate | 2026 |
| Somers Holt Developments Ltd | Construction | 2015 |
| Somers Suites Ltd | Real estate | 2024 |
| Sonerra Limited | Administrative & support | 2026 |
| Sonjaleo Ltd | Construction | 2025 |
| Sophie Alexander Accountancy Ltd | Professional & scientific | 2021 |
| Sophie Dyne Podiatry and Chiropody Limited | Health & social care | 2011 |
| Sorrell & Smith Ltd | Manufacturing | 2022 |
| Soultone Ltd | Other services | 2023 |
| Sourcing Segments Ltd | Administrative & support | 2020 |
| South East Coaches Ltd | Transport & logistics | 2017 |
| South East Construction Essex Limited | Construction | 2012 |
| South East Crane Hire Ltd | Administrative & support | 2020 |
| South East Designs Limited | Professional & scientific | 2013 |
| South East Drywall Services Ltd | Construction | 2003 |
| South East Enforcement Ltd | Financial services | 2009 |
| South East Insulation Services Ltd | Professional & scientific | 2012 |
| South East Railway Limited | Construction | 2013 |
| South Eastern Vintage & Classic Vehicle Club Limited | Other services | 2000 |
| South Essex Managed Care Ltd | Health & social care | 2011 |
| South Essex Shutters Ltd | Manufacturing | 2026 |
| South-Eastern Crane Hire Ltd | Administrative & support | 2021 |
| Southbourne Grove Denture Clinic Limited | Health & social care | 2020 |
| Southdown Plant Hire Limited | Administrative & support | 2017 |
| Southend Chauffeur Cars Ltd | Transport & logistics | 2023 |
| Southern East Asbestos Ltd | Construction | 2021 |
| Southpark Heating Services Limited | Construction | 2002 |
| Sovereign Environmental Ltd | Professional & scientific | 2025 |
| Soviet Air Force Limited | Manufacturing | 2015 |
| Space Management and Projects Ltd | Professional & scientific | 2010 |
| Space Tidy Ltd | Manufacturing | 2015 |
| Spaero Limited | Transport & logistics | 2024 |
| Spag Construction Ltd | Real estate | 2019 |
| Spanbrook RTM Company Ltd | Real estate | 2014 |
| Sparkles Cleaners Ltd | Other services | 2006 |