| Samee Frozen Food Ltd | Wholesale & retail | 2006 |
| Samuel & SON Ltd | Administrative & support | 2004 |
| Sandhurst Rest Home Ltd | Health & social care | 2005 |
| Sandringham Group PLC | | 1989 |
| Sanilo Ltd | Other services | 2020 |
| Saracen Holdings Limited | Other services | 1996 |
| Saris Leisure Group Ltd | Arts & recreation | 1977 |
| Satroc Limited | Households | 2005 |
| Savenet Limited | Information & communication | 1998 |
| Saxclasiq LLP | | 2023 |
| SCH Maxfac Limited | Health & social care | 2005 |
| Schaaf & Sons Limited | Construction | 2003 |
| SCL Ltd | Health & social care | 2007 |
| Sclater Farming Limited | Agriculture & fishing | 2023 |
| SCM Building Contractors Limited | Construction | 2007 |
| Scocles Farms Limited | Agriculture & fishing | 1986 |
| Screen Plus Limited | Manufacturing | 1987 |
| Scribes (Joinery) Ltd | Construction | 2005 |
| Seaside Property Maintenance Ltd | Real estate | 2002 |
| Seasprite Limited | Wholesale & retail | 1993 |
| Seaview (the Esplanade) Limited | Households | 1998 |
| Seaview Sussex Ltd | Information & communication | 2022 |
| Second Hand Rose Limited | Wholesale & retail | 2002 |
| Sector UK Fencing Limited | Construction | 2004 |
| Semley Management Company Limited | Households | 2003 |
| Seniko Services Limited | Other services | 2003 |
| Senlac Solutions Limited | Information & communication | 1996 |
| Sensible Heat Limited | Construction | 2004 |
| Seycal Ltd | Financial services | 2025 |
| SGW Investment Holdings Ltd | Real estate | 2019 |
| Shape the Future Limited | Professional & scientific | 2004 |
| Shaws Corner Limited | Hospitality | 1998 |
| Shearwater Developments Limited | Wholesale & retail | 1989 |
| Sheema Takeaway Ltd | Hospitality | 2004 |
| Shelley International Ltd | Extraterritorial | 2007 |
| Shelmead Limited | Wholesale & retail | 1984 |
| Shenley Recruitment Limited | Administrative & support | 2004 |
| Shhh-Holistic Limited | Wholesale & retail | 2017 |
| Shirt Logos Limited | Administrative & support | 2003 |
| Shivers Installations Limited | Construction | 1999 |
| Shivers Properties Limited | Real estate | 2000 |
| Siegerealm Limited | | 1981 |
| Sign & Strive Limited | Professional & scientific | 2022 |
| Silvatec Design Limited | Professional & scientific | 2002 |
| Simplex Electric Limited | Professional & scientific | 1926 |
| Simply RYE Limited | Wholesale & retail | 2021 |
| Simply Tiling Limited | Construction | 2003 |
| Siracs Limited | Construction | 2005 |
| Siree Aesthetics Hastings Limited | Other services | 2021 |
| Sitesculpt Limited | Information & communication | 2006 |
| Sixty Warrior Square Limited | Real estate | 1998 |
| SJM3 Limited | Professional & scientific | 2005 |
| SJM6 Limited | Professional & scientific | 2007 |
| SK Assets & Management Ltd | Real estate | 2018 |
| Skill-Is Limited | Information & communication | 2003 |
| Skinners Sheds Limited | Manufacturing | 1999 |
| Slimmerworld Limited | Extraterritorial | 2001 |
| Smallbone Estates Limited | Real estate | 1954 |
| Snowbow Productions (2000) Limited | Manufacturing | 1996 |
| Soko Publications Limited | Extraterritorial | 1983 |
| Solieac Ltd | Information & communication | 2003 |
| Solutions Accommodation Providers Limited | Hospitality | 2002 |
| Somercliff Securities Limited | | 1987 |
| SOMERS4ULT Ltd | Information & communication | 2024 |
| Somerville & Bone Ltd | Households | 2001 |
| Sopel Systems & Training Limited | Information & communication | 1998 |
| Soundcheque Limited | Information & communication | 2012 |
| Source & Edit Ltd | Administrative & support | 2007 |
| Source (South East) Limited | Construction | 2018 |
| South Cliff Avenue Management Limited | Households | 1974 |
| South Coast Hydraulics Group Limited | Professional & scientific | 1994 |
| South Coast Hydraulics Limited | Wholesale & retail | 1986 |
| South East Metal Services Limited | Construction | 2007 |
| South East Sign Services Limited | Manufacturing | 1992 |
| Southdown Surveyors Limited | Other services | 2007 |
| Southern Commercial Sales Limited | Wholesale & retail | 2003 |
| Southern Counties (Crawley) Limited | Wholesale & retail | 2002 |
| Southern Haulage Limited | Transport & logistics | 1984 |
| Southern Pools Limited | Construction | 2003 |
| Southern Rover Owners' Club Limited(The) | Arts & recreation | 1984 |
| Southern Surveys Limited | Professional & scientific | 1990 |
| Southern Swimming Pools Limited | Construction | 2003 |
| Southern Taxis (Brighton) Limited | Transport & logistics | 2002 |
| Southern Taxis (UK) Limited | Professional & scientific | 1984 |
| Southgate Business Solutions Limited | Professional & scientific | 2007 |
| Sovereign Business Solutions UK Limited | Professional & scientific | 2002 |
| Sovereign Financial Planning Ltd | Financial services | 2005 |
| Space Insight Limited | Information & communication | 2005 |
| Spark Media Communications Limited | Professional & scientific | 2006 |
| Speak-It Limited | Information & communication | 1996 |
| Special Delivery Cards Ltd | Manufacturing | 2006 |
| Specview Limited | Information & communication | 1999 |
| Spiritual Growth Ltd | Transport & logistics | 2006 |
| Spirobind Systems International Limited | Transport & logistics | 1986 |
| Splash Point Limited | Households | 2007 |
| Spoolfinder Limited | Construction | 1985 |
| Spring Harvest | Other services | 1992 |
| Spring Harvest Holidays NO 2 Limited | Extraterritorial | 2002 |
| Springfield Road Childrens Homes Ltd | Health & social care | 2002 |
| Springfield Road Management (Brighton) Limited | Households | 1999 |