| Sallis Ltd | Professional & scientific | 2021 |
| Salubrious Sauce Co Limited | Manufacturing | 2016 |
| Sanctuary Space Limited | Health & social care | 2021 |
| Sandpiper Property Company Ltd | Real estate | 2023 |
| Sanseb Limited | Professional & scientific | 2017 |
| Sapphire Cooling Services Limited | Energy | 1998 |
| Sarah Anne Interiors Limited | Wholesale & retail | 2002 |
| Sarah Byrom Consulting Limited | Professional & scientific | 2016 |
| Sarah Symonds Property Limited | Real estate | 2023 |
| Sash Windows (1686) Ltd | Manufacturing | 2006 |
| Saunders-Roe Helicopter Limited | Extraterritorial | 2000 |
| Saxbys Hair Salon Limited | Other services | 2014 |
| Saxon Growth Ltd | Professional & scientific | 2026 |
| SB Film Services Limited | Information & communication | 2012 |
| Sb-Timber & Fencing Ltd | Wholesale & retail | 2022 |
| SBC Services (East Anglia) Limited | Construction | 2020 |
| Scanning Electron Microscope Technology Limited | Professional & scientific | 1988 |
| Scarlett Joy Ventures Limited | Professional & scientific | 2000 |
| SCB Property Services Limited | Other services | 1993 |
| Schoffields (Laundry) Ltd | Other services | 2021 |
| Schoffields Ltd | Other services | 2014 |
| School's OUT Activities Ltd | Arts & recreation | 2017 |
| Sciapod Limited | Education | 2014 |
| Scipio Accounting Services Limited | Professional & scientific | 2024 |
| Scoot-Williams Holdings Limited | Financial services | 2025 |
| Scoot-Williams Limited | Professional & scientific | 2026 |
| Scorchtek Limited | Manufacturing | 2026 |
| Screen Excellence Ltd | Manufacturing | 2005 |
| Sdan Coaching Limited | Education | 2021 |
| Sea Quest Suffolk Ltd | Administrative & support | 2023 |
| Seaview Holiday Services Ltd | Real estate | 2020 |
| Seckford Golf Club (Woodbridge) Ltd | Arts & recreation | 2014 |
| Seckford Group Limited | Financial services | 2023 |
| Seckford Wines Holdings Limited | Financial services | 2019 |
| Seckford Wines Limited | Wholesale & retail | 1985 |
| Secretariat Limited | Professional & scientific | 2003 |
| Secureshed Ltd. | Information & communication | 2017 |
| Seekay UK Limited | Construction | 2003 |
| Servicered Limited | Extraterritorial | 2003 |
| Sewell Hewitt (Farms) Limited | Agriculture & fishing | 1961 |
| SGE Plastering Ltd | Construction | 2023 |
| SGS Services EA Ltd | Wholesale & retail | 2026 |
| Shakay Ltd | Real estate | 2003 |
| Sharon Cudworth Photography Ltd | Professional & scientific | 2021 |
| Sharp Historics Ltd | Wholesale & retail | 2018 |
| Shaw Groundworks Limited | Construction | 1988 |
| Shawsgate Limited | Manufacturing | 1999 |
| Sheldon Services Limited | Professional & scientific | 1996 |
| Shelley Jessica WOO Limited | Extraterritorial | 2021 |
| Sheridans Building Services Ltd | Construction | 2011 |
| Shields Haulage Ltd | Transport & logistics | 2013 |
| Shift Plus Hire Ltd | Administrative & support | 2025 |
| Shingle Street Properties Limited | Real estate | 2021 |
| Shingle Street Settlement Limited | Households | 1997 |
| Shipwright's Yard Limited | Transport & logistics | 2023 |
| Shopov Agricultural Services (SAS) Limited | Agriculture & fishing | 2007 |
| Shore Thing Consulting Limited | Professional & scientific | 2018 |
| Shottisham Campsite Limited | Hospitality | 2024 |
| Sichern Architectural Hardware Limited | Wholesale & retail | 2018 |
| Sidereal Limited | Information & communication | 2018 |
| Sidhu Medical Services Limited | Health & social care | 2021 |
| Sierra Leisure Products Limited | Wholesale & retail | 1992 |
| Sierra Space Heating Limited | Manufacturing | 1995 |
| Silver Hoof Horsemanship CIC | Agriculture & fishing | 2025 |
| Silverhand Limited | Manufacturing | 2012 |
| Simba Cricket Academy CIC | Manufacturing | 2021 |
| Simba Sports Without Boundaries CIC | Administrative & support | 2021 |
| Simon Benton Design Ltd | Professional & scientific | 2013 |
| Simon Drane Consulting Ltd | Professional & scientific | 2020 |
| Simon Moore Garden Design Ltd | Administrative & support | 2017 |
| Simon Sturgis Limited | Professional & scientific | 2018 |
| Simon's Green Plants Ltd | Agriculture & fishing | 2024 |
| Simpsons (East Anglia) Limited | Water & waste | 2009 |
| Sisterfields Limited | Real estate | 2025 |
| Sisu Real Estate Limited | Real estate | 2022 |
| Siswanto TM Ltd | Construction | 2025 |
| Siterite Property Ltd | Households | 2020 |
| Siterite Solutions Ltd | Administrative & support | 2013 |
| Siula Limited | Professional & scientific | 2017 |
| SJB Woodbridge Limited | Real estate | 2017 |
| SJM Law Limited | Professional & scientific | 2012 |
| SJR Energy Associates Ltd | Professional & scientific | 2021 |
| Sleepsafe Limited | Construction | 2006 |
| Sleepspec Ltd | Wholesale & retail | 2025 |
| Smartcall Ltd | Other services | 2016 |
| Smashing Wines Limited | Wholesale & retail | 2016 |
| SMH Project Consulting Limited | Professional & scientific | 2011 |
| Smith & Saunders Electrical Ltd | Construction | 2019 |
| Smiths of Suffolk Ltd | Agriculture & fishing | 2022 |
| SMJ Surveying Ltd | Professional & scientific | 2013 |
| Snooty Goose Limited | Hospitality | 2016 |
| Society for Sustainable Agriculture | Professional & scientific | 2020 |
| Soil Moisture Sense Ltd | Agriculture & fishing | 2011 |
| Solar Thermal Association Limited | Professional & scientific | 2010 |
| Solutions Environmental Systems Limited | Professional & scientific | 2003 |
| Sophie Cook Porcelain Limited | Administrative & support | 2021 |
| Soroc Technology (UK) Inc. | | 2017 |
| Sorrel Meadow (Hollesley) Residents Management Company Ltd | Households | 2011 |
| Sortlane Holdings Limited | Financial services | 2010 |
| Sortlane Limited | Real estate | 1990 |