| Spraybake Trustee Limited | Financial services | 2026 |
| Spraybooth Technology Limited | Manufacturing | 1993 |
| Springfields Pre-School Limited | Education | 2012 |
| Spruce Consultancy Company Limited | Wholesale & retail | 2022 |
| Square 1 Productions Ltd | Information & communication | 2018 |
| SR Lighting Limited | Administrative & support | 2018 |
| SRL Technical Services Ltd | Professional & scientific | 1967 |
| SST Select Shipping and Trading Ltd | Financial services | 2022 |
| ST Francis Tower RTM Company Limited | Households | 2015 |
| ST Luke's Park (Guildford) Management Limited | Households | 2000 |
| ST. Peters Financial Planning Ltd | Financial services | 2020 |
| Stagg Garden Services Ltd | Administrative & support | 2016 |
| Staghill Software Ltd | Information & communication | 2025 |
| Stan Professional Cleaning Services Ltd | Administrative & support | 2025 |
| Stangrave Mews Management Limited | Households | 2006 |
| Stannard Way Management Limited | Households | 2015 |
| Stanstead Village Community Centre & Social Club C.I.C. | Hospitality | 2025 |
| Stardom Warriors Ltd | Information & communication | 2024 |
| Steel Heel Pictures Limited | Information & communication | 2018 |
| Steel Property Holdings Ltd | Real estate | 2023 |
| Steel-Johnstone Limited | Extraterritorial | 1978 |
| Stella Top Music Limited | Arts & recreation | 2008 |
| Stellar Catering Ltd | Wholesale & retail | 2020 |
| Stephanie Delaney Consulting Limited | Health & social care | 2020 |
| Stephen Harvey KC Limited | Professional & scientific | 2025 |
| Stephen John Bennett Limited | Public administration | 2025 |
| Stephen Walters & Sons Limited | Manufacturing | 1899 |
| Steve's Close Management Company Ltd | Households | 2022 |
| Stevie Herbert Design Limited | Arts & recreation | 2003 |
| Stiff Properties Ltd | Real estate | 2024 |
| Stiletto Systems Limited | Public administration | 2013 |
| Stilla Navis Limited | Wholesale & retail | 2024 |
| Stingr Tech Ltd | Information & communication | 2026 |
| Stirling Aesthetics and Laser Limited | Other services | 2023 |
| STL Holdings (Chester) Limited | Financial services | 2024 |
| STL Manufacturing Limited | Manufacturing | 2006 |
| Stoneylands Facility Management CIC | Arts & recreation | 2021 |
| Storford Services Limited | Construction | 2024 |
| Storm Mcqueen Coaching Limited | Professional & scientific | 2017 |
| Stour Business Partners Limited | Professional & scientific | 2014 |
| Stour Court Flats (Sudbury) Limited | Real estate | 1999 |
| Stour Property Ltd | Real estate | 2024 |
| Stour Valley Apiaries Limited | Agriculture & fishing | 2015 |
| Stour Valley Garage Ltd | Wholesale & retail | 2021 |
| Stour Valley Joinery Ltd | Manufacturing | 2014 |
| Stour Valley Management Services Limited | Professional & scientific | 1989 |
| Stour Valley Software Limited | Information & communication | 1994 |
| Stour Valley Traffic Management Ltd | Transport & logistics | 2023 |
| Strategy & Business Management Limited | Professional & scientific | 2004 |
| Streemliner Limited | Information & communication | 2016 |
| Stretch Scenic Ltd | Arts & recreation | 2020 |
| Stronghold Ltd | Administrative & support | 2024 |
| Strzemiecki-Logistics Ltd | Transport & logistics | 2019 |
| STS Trading Solutions Limited | Professional & scientific | 2021 |
| Stuart West Photography Ltd | Professional & scientific | 2011 |
| Stuarts Drive Management Company Limited | Real estate | 2017 |
| SUB Corp Limited | Hospitality | 2019 |
| Subh Tech Ltd | Wholesale & retail | 2017 |
| Subtract Ltd | Construction | 2022 |
| Sudbury & South Suffolk Citizens Advice Limited | Health & social care | 2007 |
| Sudbury (Suffolk) & District Cricket Club C.I.C. | Arts & recreation | 2019 |
| Sudbury Arts Centre CIC | Arts & recreation | 2025 |
| Sudbury Blinds Ltd | Construction | 2024 |
| Sudbury CAB Company Limited | Transport & logistics | 2015 |
| Sudbury Chimney Specialists Limited | Construction | 2011 |
| Sudbury Choc C.I.C. | Other services | 2017 |
| Sudbury Convenience Store Ltd | Wholesale & retail | 2020 |
| Sudbury Driver Supply Ltd | Professional & scientific | 2023 |
| Sudbury Edge Limited | Hospitality | 2024 |
| Sudbury Electrical Limited | Construction | 2002 |
| Sudbury Kitchens & Bathrooms Limited | Construction | 2003 |
| Sudbury Plants Limited | Wholesale & retail | 2023 |
| Sudbury Print Group Limited | Manufacturing | 2002 |
| Sudbury Property EN Ltd | Real estate | 2025 |
| Sudbury Railways Isolations Ltd | Construction | 2015 |
| Sudbury RH Stores Ltd | Wholesale & retail | 2026 |
| Sudbury Self Storage Limited | Other services | 2012 |
| Sudbury Self Store Limited | Extraterritorial | 2012 |
| Sudbury Silk Mills Limited | Financial services | 2018 |
| Sudbury Symphony Limited | Arts & recreation | 2017 |
| Sudbury Transport Services Limited | Wholesale & retail | 2024 |
| Sudbury Tyres Limited | Wholesale & retail | 2026 |
| Sudbury Yoga Ltd | Other services | 2023 |
| Suffolk Adventure Golf Limited | Arts & recreation | 2022 |
| Suffolk and Norfolk Roofing Limited | Construction | 2025 |
| Suffolk Backyard BBQ Ltd | Hospitality | 2025 |
| Suffolk Befriending Scheme for People With Learning Disabilities | Health & social care | 1998 |
| Suffolk Chefs Ltd | Hospitality | 2019 |
| Suffolk Creative Spaces Limited | Information & communication | 2024 |
| Suffolk EAR Clinic Limited | Other services | 2025 |
| Suffolk Edge Limited | Hospitality | 2022 |
| Suffolk Gauges Limited | Manufacturing | 1986 |
| Suffolk Glass (UK) Limited | Manufacturing | 2004 |
| Suffolk Golf Limited | Arts & recreation | 2018 |
| Suffolk IT Limited | Information & communication | 2023 |
| Suffolk Landscapes and Groundworks Ltd | Administrative & support | 2023 |
| Suffolk Laser Solutions Ltd | Administrative & support | 2026 |
| Suffolk Medical and Beauty Clinic Ltd. | Health & social care | 2016 |
| Suffolk Medical Clinic Ltd. | Health & social care | 2005 |
| Suffolk Medical Holdings Ltd | Financial services | 2019 |