| Semita Living Ltd | Professional & scientific | 2025 |
| Sequoia Way Limited | Professional & scientific | 2007 |
| Shake Festival CIC | Arts & recreation | 2021 |
| Shean Lettings Ltd | Real estate | 2026 |
| Sheep Cottages Management Company Limited | Extraterritorial | 2008 |
| Shield Marine Europe Limited | Manufacturing | 2015 |
| Shotts Meadow (Management) Ltd | Households | 2024 |
| SHR Health Ltd | Administrative & support | 2015 |
| Siabod Properties Ltd | Households | 2026 |
| Sibton Country Supplies Limited | Wholesale & retail | 1999 |
| Since 72 Ltd | Professional & scientific | 2021 |
| SIR & Co Barbers Ltd | Other services | 2021 |
| Skin Deep (Woodbridge) Limited | Other services | 2011 |
| SM Reeves Agricultural Services Ltd | Agriculture & fishing | 2018 |
| Smifert Productions Limited | Information & communication | 2014 |
| Smith & Wesby (Saxmundham) Limited | Wholesale & retail | 1973 |
| Snape Antiques Centre Ltd | Wholesale & retail | 2019 |
| Snape Express Hand Car Wash Ltd | Administrative & support | 2024 |
| Snape Maltings | Education | 2016 |
| Snape Maltings Enterprises Limited | Arts & recreation | 2016 |
| Snape Maltings Projects Limited | Arts & recreation | 2016 |
| Snape Maltings Trading Limited | Wholesale & retail | 1980 |
| Snape Motor Company Limited | Wholesale & retail | 2001 |
| Snape Shipping Limited | Professional & scientific | 2015 |
| Society for the Preservation of Human Connection Ltd | Financial services | 2024 |
| Sovereign FOX Limited | Real estate | 2025 |
| Soverignfox Estates Ltd | Real estate | 2026 |
| Spartak Trading Limited | Real estate | 2012 |
| Spice Zone Restaurant Ltd | Hospitality | 2024 |
| Spinnaker Projects Limited | Construction | 2020 |
| ST. James Court (Saxmundham) Management Company Limited | Real estate | 1990 |
| Status Creative CIC | Arts & recreation | 2023 |
| Stealth Storage and Removals Ltd | Transport & logistics | 2025 |
| Stealth Storage Solutions Ltd | Transport & logistics | 2021 |
| Steel Sculptures Limited | Arts & recreation | 2014 |
| Stewart + Jaques Architects LLP | | 2026 |
| Substation Action Save East Suffolk Limited | Other services | 2021 |
| SUE Townsend Garden Design Limited | Administrative & support | 2015 |
| Suffolk 3DPRINTS Ltd | Manufacturing | 2024 |
| Suffolk and Norfolk Firewood Ltd | Extraterritorial | 2023 |
| Suffolk Arts Club Limited | Professional & scientific | 2017 |
| Suffolk Coast Developers Ltd | Construction | 2019 |
| Suffolk Dining Limited | Hospitality | 2011 |
| Suffolk Joinery Ltd | Manufacturing | 2023 |
| Suffolk Shed Ltd | Arts & recreation | 2023 |
| Suffolk VW Campers Limited | Administrative & support | 2013 |
| Sugrue Construction Ltd | Construction | 2019 |
| Susan Page Ltd | Wholesale & retail | 2026 |
| Svelte Stays Limited | Hospitality | 2013 |
| Szwed Construction Ltd | Construction | 2025 |
| T D C Groundworks Limited | Construction | 2014 |
| T Wright Logistics Limited | Transport & logistics | 2011 |
| T.O.P.O. Wangford Management Company Limited | Households | 2013 |
| Tagoma Limited | Professional & scientific | 2026 |
| Tahanan Properties Ltd | Real estate | 2025 |
| Tailor Made Resources Ltd | Administrative & support | 2002 |
| Taliare Holdings Limited | Real estate | 2020 |
| Tannington Hall Farms Limited | Extraterritorial | 2019 |
| Tannington Pigs Limited | Agriculture & fishing | 1960 |
| Tannington Transport Limited | Transport & logistics | 2003 |
| Tap.Social Ltd | Professional & scientific | 2026 |
| Tarnya's Homemade Ltd | Wholesale & retail | 2022 |
| Tarsec Medical Ltd | Wholesale & retail | 2022 |
| Tgfeller Radiological Protection Limited | Professional & scientific | 2014 |
| Thai Cafe Aldeburgh Ltd | Hospitality | 2023 |
| Thames Fort Limited | Information & communication | 2013 |
| Thameside Associates Limited | Financial services | 2022 |
| THE Autovac Manufacturing Co. Ltd | Manufacturing | 2017 |
| THE Beautiful Skin Clinic Ltd | Health & social care | 2013 |
| THE Chantry Kitchen Limited | Hospitality | 2022 |
| THE Cleaning Company Suffolk Limited | Administrative & support | 2015 |
| THE Friston Chequers Limited | Hospitality | 2021 |
| THE International Maritime Fumigation Organisation Limited | Transport & logistics | 1994 |
| THE Iris Group East Anglia Limited | Construction | 2021 |
| THE Old Creamery Residents (Halesworth) Ltd | Households | 2026 |
| THE One Stop Carpet Shop Limited | Wholesale & retail | 2015 |
| THE Opera Trust | Arts & recreation | 2007 |
| THE Plastic Handrail Company Limited | Construction | 2020 |
| THE Pocket Pubco Limited | Hospitality | 2021 |
| THE PUG and the Pussycat Limited | Wholesale & retail | 2014 |
| THE PUG and the Pussycat Online Limited | Wholesale & retail | 2018 |
| THE Re-Adjust Think Tank Ltd | Education | 2025 |
| THE Royal Oak Laxfield Ltd | Hospitality | 2026 |
| THE Saxmundham & District Community Interest Company | Health & social care | 2007 |
| THE Sentinel Drivers Club Ltd. | Other services | 2023 |
| THE Stove & Flue Company Ltd | Construction | 2023 |
| THE Suffolk Candle Company Ltd | Other services | 2016 |
| THE Sunflower Community Care Farm CIC | Administrative & support | 2016 |
| THE Toll House Accommodation Limited | Hospitality | 2003 |
| THE Wild Meat Company Limited | Manufacturing | 2000 |
| THE Woodpeckers Firewood Ltd | Agriculture & fishing | 2024 |
| THE Woodside Services Group Ltd | Real estate | 2026 |
| Thechamberofpottery Ltd | Construction | 2025 |
| Thinkavellana Ltd | Health & social care | 2021 |
| Thomas's Fine Foods Limited | Wholesale & retail | 1997 |
| Thorington Estate Limited | Agriculture & fishing | 2015 |
| Three Sixty Property Solutions Ltd | Real estate | 2016 |
| Three Sixty Risk Management Limited | Professional & scientific | 2014 |
| Tillstream Construction Consultants Ltd | Construction | 2010 |
| Titanium Fitness Ltd | Arts & recreation | 2022 |