| Stacx Modular Ltd | Construction | 2026 |
| Stahls' UK (Europe) Ltd | Manufacturing | 2000 |
| Stanbury Roofing Contractors Ltd | Construction | 2023 |
| Standbrella Limited | Other services | 2021 |
| Stane Street Charter Limited | Professional & scientific | 2023 |
| Stanley Thermal Group Ltd | Construction | 2025 |
| Stanstead Court (Hoddesdon) Management Limited | Households | 2011 |
| Stanstrete Field RTM Company Limited | Households | 2012 |
| Stanton Resources Limited | Manufacturing | 2014 |
| Star Operations Chelmsford Limited | Hospitality | 2015 |
| Starck Associates Ltd | Manufacturing | 2011 |
| Stark Projects Ltd. | Information & communication | 2017 |
| Starlight Care Partnership Ltd | Administrative & support | 2025 |
| Starling&Brook Builders Ltd | Construction | 2025 |
| Starmo Auto Electrics Ltd | Wholesale & retail | 2008 |
| Starter Formations Limited | Administrative & support | 2024 |
| Startup 101 Limited | Professional & scientific | 2026 |
| Status a Limited | Construction | 2017 |
| Stbpo Rentals Ltd | Real estate | 2024 |
| Stead Accountancy Limited | Professional & scientific | 2026 |
| Stef Plastics Limited | Manufacturing | 1984 |
| Stephen King Wealth Management Limited | Other services | 2022 |
| Stephen Waud Architectural Services Limited | Professional & scientific | 2014 |
| Stepwoods Financial Planning Ltd | Professional & scientific | 2024 |
| Steri Products Limited | Manufacturing | 2014 |
| Sterling Compliance Group Limited | Professional & scientific | 2026 |
| Sterling Washroom Services Limited | Administrative & support | 2012 |
| Steve Nokes Maintenance Ltd | Construction | 2016 |
| Steven Rich Property Management Ltd | Real estate | 2024 |
| Steward Environmental Services Ltd | Water & waste | 2021 |
| Stewart Property & Development Ltd | Construction | 2024 |
| Stewarts Properties Ltd | Real estate | 2023 |
| Sticky Pickle Company Ltd. | Hospitality | 2016 |
| Stig's Grab Services Ltd | Administrative & support | 2015 |
| Still Oak Developments Ltd | Construction | 2026 |
| Stisted Pattiswick Bradwell Parish Magazine CIC | Information & communication | 2025 |
| STL Project Services Ltd | Professional & scientific | 2023 |
| Stock Property Ltd | Real estate | 2020 |
| Stone & Simpson Limited | Construction | 2019 |
| Stonebase Limited | Manufacturing | 2006 |
| Stoneley Park House Properties Limited | Real estate | 2015 |
| Stonevale Living Ltd | Real estate | 2026 |
| Store Products Limited | Professional & scientific | 2012 |
| Stour Employment Limited | Administrative & support | 2017 |
| Stour House Consulting Limited | Professional & scientific | 2023 |
| Straker Tech UK Limited | Administrative & support | 2015 |
| Stranders Health Ltd | Other services | 2025 |
| Strands Fundraising CIC | Professional & scientific | 2022 |
| Strange Enterprises Limited | Arts & recreation | 2021 |
| Strategic Recruitment Services Ltd | Information & communication | 2022 |
| Streetlight Capital Ltd | Professional & scientific | 2022 |
| Strengthener Limited | Health & social care | 2015 |
| Striking Management Limited | Administrative & support | 2022 |
| Strong Clad Facades Limited | Construction | 2024 |
| Strong Clad Limited | Construction | 2006 |
| Stuart Castle Limited | Professional & scientific | 1981 |
| Stuart Day Electrical Installations Limited | Construction | 2003 |
| Studio Bespoke London Ltd | Manufacturing | 2024 |
| Studio Starling Ltd. | Wholesale & retail | 2015 |
| Studyaxis Global Ltd | Education | 2025 |
| Subcool Air Conditioning East Anglia Limited | Energy | 2025 |
| Suburban & City Developments Ltd | Construction | 2019 |
| Success in Schools Ltd | Education | 2010 |
| Suddenly Comics Ltd. | Other services | 2011 |
| Suffolk Fabrications Limited | Administrative & support | 2004 |
| Sukha Ltd | Hospitality | 2025 |
| Summer Shine Ltd | Administrative & support | 2014 |
| Summerbrass Ltd | Hospitality | 2022 |
| Summerleaze Holding Ltd | Real estate | 2021 |
| Summit Brook Ltd | Other services | 2025 |
| Sun Products UK Limited | Manufacturing | 1995 |
| Sun Properties Limited | Real estate | 2001 |
| Sunbrero Foods Ltd | Hospitality | 2024 |
| Sunbury Developments LLP | | 2012 |
| Sunbury Homes (Cranham) LLP | | 2011 |
| Sunbury Homes (Darsham) LLP | | 2016 |
| Sunbury Homes (Holdings) Limited | Financial services | 2011 |
| Sunchild Creations Ltd | Other services | 2024 |
| Sunny Days Childrens Fund | Other services | 2006 |
| Sunny Scorpion Ltd | Professional & scientific | 2025 |
| Sunrise AKA Limited | Health & social care | 2018 |
| Sunshine Properties Essex Ltd | Real estate | 2022 |
| Super Kilmanock Ltd | Administrative & support | 2016 |
| Sure Start Health Care Ltd | Health & social care | 2010 |
| Surefix Plumbing Ltd | Construction | 2026 |
| Susanna’S Prime Dog PAD Ltd | Other services | 2023 |
| Sushi OLA Land Limited | Hospitality | 2024 |
| Sustainable Ethical Enterprises Limited | Wholesale & retail | 2016 |
| Sutherland Partners Ltd | Agriculture & fishing | 2013 |
| Sutton Tools UK Limited | Manufacturing | 1980 |
| Svasti Management Ltd | Extraterritorial | 2011 |
| SW Renovations Limited | Construction | 2020 |
| Swallowfield Computers Limited | Information & communication | 1994 |
| Swaminarayan Limited | Wholesale & retail | 2026 |
| Swandels Horticultural Services Limited | Administrative & support | 2021 |
| Swann Engineering Group Ltd. | Manufacturing | 1974 |
| Swann Group Limited | Professional & scientific | 2005 |
| Swann I&M Services Limited | Construction | 2007 |
| SWB Developments Limited | Construction | 2026 |
| SWB House Limited | Other services | 2026 |