| Siteset Services Ltd | Information & communication | 2024 |
| Sizzat@Soulfresh Ltd | Arts & recreation | 2019 |
| SJT Contracts Limited | Construction | 2017 |
| SK Private Holdings Limited | Financial services | 2022 |
| SK SPV Ltd | Real estate | 2024 |
| Skin Republic Aesthetics Ltd | Other services | 2024 |
| Skin Studio Ltd | Other services | 2023 |
| Skinex Ltd | Wholesale & retail | 2017 |
| Skyco Bathrooms and Tiling Limited | Construction | 2025 |
| Skyline 120 Courtyard Management Limited | Households | 2006 |
| Skyships Automotive Limited | Manufacturing | 1998 |
| Skyships Limited | Manufacturing | 1995 |
| Skyships Productions Limited | Manufacturing | 1998 |
| Slashsrc Ltd | Information & communication | 2024 |
| Slate Lane Properties Ltd | Real estate | 2018 |
| Sles Originals Ltd | Information & communication | 2024 |
| SLJ Studio Ltd | Manufacturing | 2026 |
| Slocum Bligh Limited | Real estate | 2016 |
| Slow Play Productions Limited | Extraterritorial | 2015 |
| Slurp Creative Design Ltd | Professional & scientific | 2021 |
| SM Technology Solutions Ltd | Professional & scientific | 2025 |
| Smart Education Solutions Ltd. | Information & communication | 2015 |
| Smart Fire Door Services Ltd | Construction | 2023 |
| Smart Service Solutions Limited | Financial services | 2016 |
| Smith & SON Land Maintenance Ltd | Administrative & support | 2022 |
| Smith & Watts Limited | Manufacturing | 1968 |
| Smith Land & Development Ltd | Construction | 2021 |
| Smiths Bagels Limited | Hospitality | 2022 |
| SMK Scaffolding Services Limited | Construction | 2025 |
| Smoke Truck Ltd | Hospitality | 2025 |
| Smokey Heaven BBQ Ltd | Manufacturing | 2020 |
| Snappd Ltd | Information & communication | 2016 |
| Sneath Estates Property Management Ltd | Real estate | 2023 |
| Snowhill Land and Development Ltd. | Real estate | 2015 |
| SO Prime Accountancy Ltd | Professional & scientific | 2026 |
| Social Spirits Ltd | Hospitality | 2024 |
| Social Work Partners Limited | Administrative & support | 2020 |
| Socialtech.Investments Ltd | Financial services | 2025 |
| Sofi's Turizm UK Ltd | Other services | 2022 |
| Softlink Solutions Limited | Information & communication | 1998 |
| Soins Care Ltd | Health & social care | 2015 |
| Solar MAN Ltd | Construction | 2025 |
| Solar Power (GB) Ltd | Energy | 2007 |
| Solar Power (UK) Ltd | Energy | 2012 |
| Solmaserv Ltd | Manufacturing | 2019 |
| Solution 47 Recruitment Limited | Administrative & support | 2021 |
| Solution Repair Ltd | Professional & scientific | 2023 |
| SOLUTION4YOU Ltd | Transport & logistics | 2021 |
| Solve My Problem Ltd | Information & communication | 2018 |
| Something Beginning With Ltd | Wholesale & retail | 2023 |
| Something Scrummy Ltd | Hospitality | 2021 |
| Somni Limited | Professional & scientific | 2024 |
| Soraf Drainage Limited | Construction | 2025 |
| SOS Plastering Services Limited | Construction | 2012 |
| Sounds & Pictures Ltd | Professional & scientific | 2007 |
| Sourbro Ltd | Manufacturing | 2025 |
| South East Property Partnership Limited | Real estate | 2025 |
| South Eastern Air Conditioning (London) Limited | Energy | 2015 |
| South Eastern Air Conditioning Limited | Energy | 2013 |
| South Eastern GAS Services Ltd | Construction | 2020 |
| South Eastern Property Limited | Real estate | 2024 |
| South Street Braintree Ltd | Administrative & support | 2023 |
| South West Paper Recycling Ltd | Water & waste | 2013 |
| Southsea Ozel Property Holdings Limited | Real estate | 2021 |
| Southweb Limited | Professional & scientific | 2005 |
| Spacetech.Investments Ltd | Financial services | 2025 |
| Spalls Clean Limited | Administrative & support | 2023 |
| Spanish Legal Services Ltd | Information & communication | 2023 |
| Sparkling Healthcare Ltd | Administrative & support | 2015 |
| Sparks Farm (Essex) Ltd | Agriculture & fishing | 2024 |
| Sparrow Decor Ltd | Construction | 2014 |
| SPB Homes Limited | Real estate | 1991 |
| Spectrumddp Ltd | Construction | 2025 |
| Speech Development Limited | Arts & recreation | 2009 |
| Speech Development Productions Ltd | Information & communication | 2023 |
| Speech Development Properties Limited | Real estate | 2021 |
| Speed & Swift Ltd | Transport & logistics | 2022 |
| Speedshot Ltd | Professional & scientific | 2025 |
| Speller Plumbing Services Ltd | Construction | 2018 |
| Spencer-Lambart Window Displays Ltd | Professional & scientific | 2025 |
| Spenser Road Management Limited | Households | 1988 |
| Spice Hub Braintree Limited | Hospitality | 2025 |
| Sports Facility Services Limited | Arts & recreation | 2013 |
| Sports, Media and Entertainment Wealth Management Limited | Professional & scientific | 2023 |
| Spotless Cleaning Support Services Limited | Administrative & support | 2024 |
| Spotlesssy Cleaning Ltd | Other services | 2025 |
| Springfield Knee Centre Limited | Health & social care | 2016 |
| Springwood Cafe and Grill Ltd | Hospitality | 2026 |
| Springwood Meats Limited | Wholesale & retail | 2014 |
| Squeeky Clean Home & Office Cleaning Ltd | Administrative & support | 2017 |
| Squeezed Orange Ltd | Manufacturing | 2016 |
| Squirrel Digital Group Limited | Information & communication | 2018 |
| SRB Assets Ltd | Wholesale & retail | 2026 |
| SRB Consult Ltd | Professional & scientific | 2010 |
| SRM Forwarding Ltd | Transport & logistics | 2023 |
| SRP and Partners Group Ltd | Construction | 2025 |
| Ssocm Ltd | Professional & scientific | 2013 |
| ST. Andrew Mews Management Co. Limited | Households | 1982 |
| ST. Mary's Mews (Tollesbury) Management Limited | Households | 1989 |
| Stacey Cosens Marketing Limited | Professional & scientific | 2019 |