| Smugglers Weddings Ltd | Hospitality | 2013 |
| Sobnest Ltd | Wholesale & retail | 2022 |
| Social Expert Trading Ltd | Professional & scientific | 2022 |
| Sognomio Ltd | Wholesale & retail | 2024 |
| Soil Knot Ltd | Wholesale & retail | 2025 |
| Solutions for Leisure Ltd. | Administrative & support | 2005 |
| Somersham Properties Limited | Real estate | 1985 |
| Sonata Solutions Limited | Information & communication | 2007 |
| Sorold Group Ltd | Wholesale & retail | 2024 |
| Soundwave Entertainments Ltd | Arts & recreation | 2022 |
| South LEE School Limited | Education | 1961 |
| Southwold Harbour Cafe Limited | Hospitality | 2018 |
| Sparkle Stays Ltd | Hospitality | 2022 |
| SPC Printers Limited | Manufacturing | 2006 |
| Specialized Print Limited | Manufacturing | 1991 |
| Spenfield Investments Limited | Extraterritorial | 2002 |
| Spero Consult Limited | Health & social care | 2019 |
| Sphere Consulting Ltd | Professional & scientific | 2025 |
| Spireway Limited | Professional & scientific | 1984 |
| Spitalfields Fabrics Limited | Professional & scientific | 1978 |
| Spitalfields Limited | Extraterritorial | 2002 |
| Sportfish Charters UK Limited | Wholesale & retail | 2002 |
| SPR Trailer Services Limited | Manufacturing | 1998 |
| Springcroft CDR Ltd | Construction | 2014 |
| Spunella,Limited | Extraterritorial | 1909 |
| Squirrel Lodge Limited | Health & social care | 2002 |
| SRH Limited | Information & communication | 2005 |
| ST Elizabeth Hospice | Health & social care | 1984 |
| ST Hedges-Quinn Limited | Arts & recreation | 2003 |
| Star Telelink Ltd | Professional & scientific | 2018 |
| Stareet (Builders) Limited | Real estate | 1977 |
| Starlight Creative Media Ltd | Information & communication | 2021 |
| Starstream Investments Limited | Extraterritorial | 2002 |
| Start NOW Today Ltd | Wholesale & retail | 2024 |
| Starvortexcraft Ltd | Wholesale & retail | 2025 |
| Steam Vibe Ltd | Wholesale & retail | 2020 |
| Stemar Limited | Professional & scientific | 2003 |
| Stemkind Ltd | Education | 2020 |
| Stephen Ford Estate Ltd | Real estate | 2024 |
| Stetchworth Limited | Real estate | 2005 |
| Steve Foley Transport Limited | Transport & logistics | 2006 |
| Steven James Allen Limited | Professional & scientific | 2006 |
| Stimbol Ltd | Hospitality | 2023 |
| Stone & Barrow Construction Ltd | Construction | 2025 |
| Stone & Barrow Ltd | Real estate | 2024 |
| Stone House Suffolk Limited | Hospitality | 2021 |
| Stonebox Limited | Financial services | 2022 |
| Storey Poultry Supplies Limited | Agriculture & fishing | 2001 |
| Stormy Growth Limited | Information & communication | 2023 |
| Stow Training Limited | Education | 2006 |
| Stowhealth Ltd | Wholesale & retail | 2001 |
| Stowupland Fast Fit Ltd. | Wholesale & retail | 1993 |
| Stradbrokes Limited | Wholesale & retail | 2007 |
| Straidvalley Management Services Limited | Professional & scientific | 2014 |
| Straighter Digital Services Limited | Information & communication | 2018 |
| Strategy First Interactive Limited | Construction | 2002 |
| Strathearn Consulting Limited | Information & communication | 2002 |
| Stratton Heating & GAS Services Limited | Construction | 2002 |
| Streamhollow Crafts Ltd | Wholesale & retail | 2025 |
| Sturdee Poultry Farms Limited | Agriculture & fishing | 1997 |
| Style Superior Windows & Conservatories Limited | Construction | 1991 |
| SU Advisory Limited | Professional & scientific | 2022 |
| Sudbury(Suffolk)Sports Ground,Limited(The) | Arts & recreation | 1919 |
| Suffolk & Essex General Trading & Investment Co. Limited | Real estate | 1977 |
| Suffolk Accounting Services Limited | Professional & scientific | 2002 |
| Suffolk Bar Ltd | Hospitality | 2026 |
| Suffolk Building Services Limited | Construction | 2001 |
| Suffolk Creations Limited | Professional & scientific | 2022 |
| Suffolk East Federation of Women's Institutes | Other services | 1993 |
| Suffolk Engineers Infinitely Variable Apportioned Drives Limited | Manufacturing | 1980 |
| Suffolk Heritage Joinery Limited | Manufacturing | 2002 |
| Suffolk Life (Spartan Estate) Limited | Real estate | 2001 |
| Suffolk Life Annuities Limited | Financial services | 1971 |
| Suffolk Life Group Limited | Financial services | 1994 |
| Suffolk Life Pensions Limited | Financial services | 1974 |
| Suffolk Life Trustees Limited | Financial services | 2007 |
| Suffolk Motor Co. Limited | | 1978 |
| Suffolk Safety Solutions Ltd | Wholesale & retail | 2025 |
| Suffox Services Ltd | Administrative & support | 2016 |
| Sugba Station UK Ltd | Hospitality | 2022 |
| Suhang Media Limited | Information & communication | 2025 |
| Summit Propertysmiths Limited | Construction | 2022 |
| Sun-Rise Installations Limited | Construction | 2004 |
| Suncloud Business Solutions Limited | Wholesale & retail | 2023 |
| Sunningdale Maintenance (Ipswich) Limited | Construction | 1958 |
| Sunwolf Ltd | Real estate | 2019 |
| Superhero Broadband Limited | Information & communication | 2016 |
| Supermoon Limited | Information & communication | 2003 |
| Supersine Duramark Group Limited | Professional & scientific | 1927 |
| Supersine Duramark Limited | Extraterritorial | 2004 |
| Surgcraft Ltd | Health & social care | 2023 |
| Sustainable Information Research and Development Ltd | Financial services | 2018 |
| Sustainsys Consulting Ltd | Information & communication | 2021 |
| Sutton Services Limited | Construction | 2000 |
| Suyuti Limited | Professional & scientific | 2024 |
| Suzana Marketing Agency Ltd | Professional & scientific | 2022 |
| Swift Leasing Company Limited | Extraterritorial | 1947 |
| Sworders Limited | Real estate | 2000 |
| SYD Capital Germany GmbH Ltd | Information & communication | 2020 |
| Synergy Financial Accountants Limited | Professional & scientific | 2025 |