| Smoothedge Ltd | Manufacturing | 2021 |
| SMR Solicitors Limited | Professional & scientific | 2016 |
| Smudge and Dribble Ltd | Wholesale & retail | 2012 |
| SMW Concessions Ltd | Hospitality | 2026 |
| SN Roebuck Ltd | Information & communication | 2021 |
| Snable Ltd | Hospitality | 2023 |
| Snake Height Ltd | Administrative & support | 2022 |
| Snarms Ltd | Financial services | 2024 |
| Snowhill Ltd | Wholesale & retail | 1996 |
| Soap Street Ltd | Manufacturing | 2024 |
| Soapy and Bubbly Ltd | Manufacturing | 2021 |
| Society of Professional Economists | Other services | 1960 |
| Society of Technical Analysts Limited | Other services | 1986 |
| Socium Search Limited | Administrative & support | 2017 |
| Socrates CRM Ltd | Information & communication | 2024 |
| Softech Rail Limited | Information & communication | 2005 |
| Softronic Solutions Limited | Information & communication | 1988 |
| Software Works for YOU Limited | Information & communication | 2012 |
| Soil Carbon Baseline Limited | Professional & scientific | 2024 |
| Solar Swap Ltd | Energy | 2021 |
| Solent Assets Ltd | Real estate | 2016 |
| Solent Helicopters Limited | Transport & logistics | 1994 |
| Solent Securities | Financial services | 1963 |
| Solent Wholesale Carpet Company Limited | Wholesale & retail | 1972 |
| Solicitors Online Limited | Professional & scientific | 2013 |
| Solid Recruitment Ltd | Administrative & support | 2012 |
| Solis Ortus Limited | Information & communication | 2021 |
| Solly Consulting Ltd | Information & communication | 2022 |
| Solo Enlighteniment Limited | Real estate | 2022 |
| Solomons Estate Agents Limited | Real estate | 2022 |
| Solprise Ltd | Information & communication | 2026 |
| Solstice Power Projects Limited | Other services | 2021 |
| Solufeed Limited | Manufacturing | 1998 |
| Solution B a Limited | Financial services | 2011 |
| Solution Synchrony Ltd | Other services | 2018 |
| Somerfield House (Selsey) Limited | Real estate | 2023 |
| Somerstown Management Company Limited | Households | 1982 |
| Something Fishy (Sussex) Limited | Wholesale & retail | 1996 |
| Sonoptics Productions Limited | Information & communication | 1999 |
| Sophie Worman Limited | Information & communication | 2019 |
| Sorbus Holdings Limited | Financial services | 2025 |
| Sorcha Sports Ltd | Wholesale & retail | 2017 |
| Sorted Health Ltd | Wholesale & retail | 2015 |
| Souls of Lights Ltd | Extraterritorial | 2021 |
| Source Artisan Limited | Wholesale & retail | 2016 |
| Souters Developments Ltd | Construction | 2018 |
| South Coast Apps Ltd | Information & communication | 2025 |
| South Coast Contractors Limited | Construction | 2003 |
| South Coast Domestic & Commercial Cleaning Ltd | Administrative & support | 2024 |
| South Coast Ecology Ltd | Professional & scientific | 2024 |
| South Coast Energy Ltd | Construction | 2011 |
| South Coast Eyes Limited | Health & social care | 2016 |
| South Coast Financial Services Limited | Financial services | 2019 |
| South Coast Group ( Holdings ) Ltd | Other services | 2017 |
| South Coast Kidz Ltd | Administrative & support | 2018 |
| South Coast Lawn Care Ltd | Administrative & support | 2023 |
| South Coast Legal Services Limited | Professional & scientific | 2014 |
| South Coast Leisure Services (Hampshire) Limited | Manufacturing | 2015 |
| South Coast Payments Ltd | Financial services | 2015 |
| South Coast Sea Gods Apparel Ltd | Wholesale & retail | 2025 |
| South Coast Sea Gods CIC | Arts & recreation | 2025 |
| South Coast Tactical Ltd | Professional & scientific | 2012 |
| South Downs Air Conditioning Solutions Ltd | Energy | 2017 |
| South Downs Autolocksmiths Ltd | Wholesale & retail | 2026 |
| South Downs Ecology Limited | Other services | 2024 |
| South Downs FM Ltd | Administrative & support | 2025 |
| South Downs Plant & Machinery Ltd | Wholesale & retail | 2023 |
| South Downs Repair Centres Ltd | Wholesale & retail | 2025 |
| South Downs Storage Arun Ltd | Transport & logistics | 2019 |
| South Downs Storage Ltd | Transport & logistics | 2010 |
| South Downs Veterinary Consultancy Ltd | Professional & scientific | 2019 |
| South East Realisations 2025 Limited | Professional & scientific | 2021 |
| South Lane Developments Limited | Construction | 2022 |
| South Sales Ltd | Wholesale & retail | 2024 |
| South West Project Services Limited | Water & waste | 2024 |
| Southbank Management (Chichester) Limited | Households | 1980 |
| Southcoast Homecare Ltd | Health & social care | 2019 |
| Southcoast Motor Services Limited | Transport & logistics | 1998 |
| Southdown Court Limited | Households | 1998 |
| Southdown Electrical Ltd | Construction | 2011 |
| Southdown House (Worthing) Residents' Association Limited | Households | 1974 |
| Southdown Stairlifts Ltd | Health & social care | 2019 |
| Southdowns Architects Limited | Professional & scientific | 2022 |
| Southdowns Chiropractic Limited | Health & social care | 2011 |
| Southdowns Management Group Limited | Financial services | 2024 |
| Southdowns Tiling Ltd | Construction | 2025 |
| Southend Farms Limited | Hospitality | 1995 |
| Southend Regen Limited | Professional & scientific | 2025 |
| Southern Area Scaffolding Services Ltd | Construction | 2025 |
| Southern Counties (Properties) Limited | Real estate | 1977 |
| Southern Counties Electrical Solutions Ltd | Energy | 2025 |
| Southern Counties Janitorial Supplies Ltd | Wholesale & retail | 2002 |
| Southern Counties Tractor Spares Ltd | Wholesale & retail | 2002 |
| Southern Cranes and Access Holdings Ltd | Administrative & support | 2017 |
| Southern Cylinder Services Limited | Manufacturing | 2015 |
| Southern Digital Templating Ltd | Construction | 2019 |
| Southern Domestic Abuse Service | Hospitality | 2012 |
| Southern Ebike Rentals Limited | Administrative & support | 2020 |
| Southern Elite Contractors Ltd | Administrative & support | 2020 |
| Southern Fire Alarms Limited | Construction | 1999 |