| Short Acre Farm Limited | Real estate | 2024 |
| Short Rent Limited | Real estate | 2019 |
| Silky Road Limited | Wholesale & retail | 2020 |
| Silver Birch Recruitment Limited | Administrative & support | 2003 |
| Simon Interior Design Limited | Construction | 2021 |
| Simple Solution Logistics Limited | Transport & logistics | 2021 |
| Simply Cakes Direct Limited | Hospitality | 2023 |
| Sirona Clinic Ltd | Health & social care | 2025 |
| Sirona Medical Ltd | Administrative & support | 2015 |
| SJD Hospitality Ltd | Hospitality | 2024 |
| SJR Advisory Ltd | Professional & scientific | 2026 |
| SK Academy Ltd | Education | 2014 |
| SK Pang Electronics Limited | Wholesale & retail | 2010 |
| SKETCH24 Limited | Administrative & support | 2022 |
| Slieverue Project Management Limited | Professional & scientific | 2016 |
| SLR Wealth Services Limited | Other services | 2011 |
| Snap Micro Ltd | Manufacturing | 2014 |
| SNK Wealth Management Limited | Professional & scientific | 2024 |
| SNP Invest UK Ltd | Real estate | 2020 |
| Social Commerce Accountants Ltd | Professional & scientific | 2021 |
| Social Hub the Agency Ltd | Information & communication | 2022 |
| Social Value SME Ltd | Professional & scientific | 2022 |
| Soils and Aggregates Limited | Other services | 2017 |
| Solar Marine Agency UK Limited | Other services | 2020 |
| Solid Stone Driveways and Patios Ltd | Professional & scientific | 2026 |
| Sorbus Court RTM Company Ltd | Households | 2015 |
| South Stortford Ltd | Hospitality | 2020 |
| Southcroft Management (Sutton) Limited | Households | 1966 |
| Southeast Ecotec Services Limited | Construction | 2023 |
| Southmill Holdings Ltd | Real estate | 2025 |
| Sovereign Design and Build Ltd | Construction | 2022 |
| Sovereign House (NO 2) Management Company Limited | Households | 1995 |
| Sovereign Specialist Services Limited | Construction | 2013 |
| Space Fitness Ltd | Arts & recreation | 2024 |
| Spacecads Ltd | Professional & scientific | 2023 |
| Sphere Security Ltd | Administrative & support | 2023 |
| Spitfire Hydraulics Limited | Manufacturing | 2026 |
| Spong Media Limited | Professional & scientific | 2025 |
| Spraytech (Stove Enamellers) Limited | Manufacturing | 1981 |
| Springham Contracts Ltd | Construction | 2017 |
| SPT Training Ltd | Education | 2023 |
| SR Digital Services Ltd | Wholesale & retail | 2015 |
| Srrd Controls Ltd | Construction | 2020 |
| ST Ives Holiday Lettings Limited | Real estate | 2021 |
| ST Mellons PUB Co Ltd | Hospitality | 2018 |
| ST Winifred's Residents' Association, Limited | Real estate | 1962 |
| ST. Erkenwald Mews Management Limited | Households | 1992 |
| ST. Georges Place Hornchurch Management Company Limited | Households | 1992 |
| ST. James Management Co. Limited | Households | 1985 |
| Stace Properties Limited | Construction | 2020 |
| Staff Partners Business Ltd | Administrative & support | 2020 |
| Staff Partners Ltd | Administrative & support | 2020 |
| Staff Partners Mental Health Ltd | Administrative & support | 2020 |
| Staff Partners Nursing Ltd | Administrative & support | 2020 |
| Stak Scaffold Limited | Construction | 2012 |
| Stanlake Surveying Limited | Construction | 2024 |
| Stansted Fluid Power (Products) Limited | Professional & scientific | 1974 |
| Starbrook Limited | Hospitality | 2000 |
| Stars Accounting Ltd | Public administration | 2020 |
| Starvin Marvins Ltd | Wholesale & retail | 2001 |
| Stayactive Allstars Ltd | Arts & recreation | 2022 |
| Steden Electrical Products Ltd | Wholesale & retail | 2011 |
| Stefania Biagini Ltd | Wholesale & retail | 2016 |
| Stephanie Louise Aesthetics Ltd | Other services | 2020 |
| Sterry House (Block B) Management Company Limited | Households | 1988 |
| Stewart & Weston Limited | Construction | 2022 |
| Stonards Farm | | 1994 |
| Stone Heat Ltd | Construction | 2012 |
| Stoneleigh Fire Consultancy Ltd | Construction | 2020 |
| Stonemasonry Solutions Ltd | Construction | 2016 |
| Storage Lockers Ltd | Other services | 2020 |
| Stort Brickwork Limited | Construction | 2000 |
| Stort Healthcare Limited | Other services | 2009 |
| Stratful Associates Limited | Professional & scientific | 2017 |
| Stratiform Business Intelligence Partners Ltd | Professional & scientific | 2025 |
| Strongerhealth.Me CIC | Health & social care | 2019 |
| STT Interiors Ltd | Construction | 2013 |
| Sulve Ltd | Construction | 2021 |
| Summit Peak Training Ltd | Education | 2010 |
| Sunstone House Development Ltd | Construction | 2018 |
| Sunstone House Ltd | Real estate | 2020 |
| Supreme CAB Co. Limited | Transport & logistics | 1988 |
| Sustainable Kitchen Consultants Ltd | Hospitality | 2018 |
| Sutherland Demolition Ltd | Construction | 2016 |
| Sutherland Investments London Ltd | Real estate | 2026 |
| Suzanne Howell Interiors Limited | Professional & scientific | 2010 |
| Swan Graphics Limited | Manufacturing | 1976 |
| Swan Scanning Limited | Professional & scientific | 1983 |
| Swish Lettings NW Ltd | Households | 2022 |
| Sykes Anderson LLP | | 2003 |
| Sykes Anderson Perry Limited | Other services | 2014 |
| Sylavie Swimwear Limited | Manufacturing | 2025 |
| Synergie Foods Ltd | Hospitality | 2025 |
| System Restore Limited | Information & communication | 2003 |
| T a Performance Limited | Administrative & support | 2010 |
| T T S Centre Limited | Wholesale & retail | 2011 |
| T T S Centre Property Ltd | Wholesale & retail | 2024 |
| T T S Corporation Limited | Professional & scientific | 2011 |
| T Wright Carpentry Ltd | Construction | 2016 |
| T&J Landscapes Services Ltd | Administrative & support | 2025 |