| Southwater Area Community Centre | Health & social care | 2001 |
| Sovhra Ltd | Financial services | 2024 |
| Sparkbuild Ltd | Construction | 2024 |
| Specialist Coatings (GB) Ltd | Manufacturing | 2000 |
| Speedinvest Limited | Information & communication | 2018 |
| Spider Enterprises Limited | Professional & scientific | 2020 |
| Spleenwort Ltd | Information & communication | 2021 |
| SPM International Group Limited | Information & communication | 2024 |
| Spongewell Limited | Professional & scientific | 2015 |
| Sporting Club Pass+Move | Arts & recreation | 2017 |
| Spotlight Dance School Ltd | Arts & recreation | 2019 |
| Spun Glass Theatre | Arts & recreation | 2015 |
| Squared Rebate Ltd | Information & communication | 2025 |
| Squarespell Limited | Information & communication | 2025 |
| ST Apollonia Oral Care Limited | Health & social care | 2014 |
| ST Apollonia Station Road Ltd | Real estate | 2026 |
| ST Helen's Court Residents Association (NO.3) Limited | Households | 1964 |
| ST Helens Crescent Limited | Households | 2006 |
| ST Helens Freedom RTM Company Limited | Households | 2022 |
| ST Helens Wood Property Ltd | Real estate | 2026 |
| ST James RD Co Ltd | Real estate | 2020 |
| ST. Andrews Villas Management Company Limited | Real estate | 1989 |
| ST. Helen's Court Residents Association (NO.2) Limited | Administrative & support | 1963 |
| ST. Leonards Court Property Management (East Sussex) Limited | Households | 1978 |
| St.Helen's Court Residents Association Limited | Real estate | 1962 |
| St.Mary's Men's Social Club Limited | Real estate | 1933 |
| Stables Trust Limited(The) | Arts & recreation | 1957 |
| Stag Electrical Contractors Ltd | Construction | 2023 |
| Stainless Brass & Glass Limited | Construction | 2000 |
| Stapley Holdings Limited | Households | 2022 |
| Star Spirit Limited | Hospitality | 2013 |
| Star Surfacing Limited | Construction | 2017 |
| Starlake Comps Ltd | Other services | 2025 |
| Startpoint Web Design Ltd | Information & communication | 2024 |
| Steady Heat Ltd | Construction | 2024 |
| Steelco (UK) Limited | Wholesale & retail | 1988 |
| Steep Hens Limited | Hospitality | 2025 |
| Stellar Property Maintenance Ltd | Construction | 2025 |
| Sterling Invested Ltd | Real estate | 2025 |
| Sterling Security Services Ltd. | Administrative & support | 2018 |
| Steve Shoesmith Plumbing & Heating Limited | Construction | 2003 |
| Stonelynk Valley | Agriculture & fishing | 2016 |
| Stonewell Drinks Company Limited | Financial services | 2011 |
| Stooge Coffee Limited | Wholesale & retail | 2021 |
| Stories Into Light Ltd | Information & communication | 2014 |
| Storm Productions Limited | Extraterritorial | 1995 |
| Stratton Asset Management Limited | Extraterritorial | 2023 |
| Stratton Wealth Management Limited | Financial services | 2019 |
| Strawberry Girl Productions Ltd | Information & communication | 2020 |
| Street Food 1066 Limited | Hospitality | 2022 |
| Strictly Media Limited | Other services | 2003 |
| Studio DC Designs Ltd | Professional & scientific | 2019 |
| Studio Mayall Limited | Professional & scientific | 2022 |
| Studio-On-Sea Ltd | Professional & scientific | 2023 |
| SU Fruits Ltd | Wholesale & retail | 2025 |
| Suga Design Limited | Professional & scientific | 2017 |
| Sulgrave Road Management Company Limited | Real estate | 1987 |
| Sunshine Music Group Limited | Arts & recreation | 2020 |
| Supplytrain C.I.C. | Professional & scientific | 2015 |
| Supreme Change Ltd | Professional & scientific | 2014 |
| Surge & Signal CIC | Arts & recreation | 2025 |
| Surge Menopause CIC | Professional & scientific | 2026 |
| Surprizes Ltd | Arts & recreation | 2025 |
| Surrey Mechanics Limited | Wholesale & retail | 2023 |
| Sussex 2 Ltd | Other services | 2018 |
| Sussex Coast (Hastings) Properties Ltd | Construction | 2013 |
| Sussex Coast Developments Limited | Real estate | 2013 |
| Sussex Coast Gifts Limited | Wholesale & retail | 2018 |
| Sussex Coast Properties (ST Marys Hall) Limited | Construction | 2016 |
| Sussex Coast Properties Limited | Real estate | 2013 |
| Suzie Thomas Limited | Other services | 2010 |
| Svps Education Limited | Professional & scientific | 2022 |
| Swain Project Consulting Ltd | Information & communication | 2022 |
| Swann Accounting Limited | Professional & scientific | 2022 |
| Swann Appointments Limited | Extraterritorial | 2024 |
| Sweet and Dandy Ltd | Professional & scientific | 2015 |
| Sweets Coffee Beans Ltd | Wholesale & retail | 2026 |
| Swirly Whirly Ltd | Hospitality | 2026 |
| Swjs Property Investment Limited | Real estate | 2018 |
| SWM Group Limited | Information & communication | 2015 |
| Symbiosis Wellbeing Ltd | Health & social care | 2019 |
| Symes Roofing Ltd | Construction | 2012 |
| Synthvision Ltd | Information & communication | 2026 |
| Systemic Change Ltd | Administrative & support | 2023 |
| T Pearce Plumbing & Heating Limited | Construction | 2013 |
| T Pearce Properties Limited | Real estate | 2018 |
| T S Bespoke Joinery Ltd | Construction | 2012 |
| T Scrumptious Limited | Hospitality | 2010 |
| T&T Future Ltd | Real estate | 2025 |
| T.C.A.M. Limited | Construction | 2001 |
| T2W Ltd | Administrative & support | 2025 |
| Talent Rockit Limited | Administrative & support | 2024 |
| Talk Event Netting Ltd | Construction | 2024 |
| Tallow Health Ltd | Wholesale & retail | 2024 |
| TAN Food Services Ltd | Hospitality | 2021 |
| Tandem Financial Direction Ltd | Professional & scientific | 2016 |
| TANKS4HIRE Limited | Administrative & support | 2023 |
| Tapas Y MAS Ltd | Hospitality | 2019 |
| Taste of Vietnam Ltd | Hospitality | 2024 |
| TC Properties Southern Limited | Real estate | 2008 |