| South East England CDA Limited | Extraterritorial | 2010 |
| South East Fabricators Ltd | Manufacturing | 2008 |
| South East Residential Home Improvements Ltd | Construction | 2025 |
| South East Security and Fire Protection Ltd | Transport & logistics | 2016 |
| South East Timber Frame Ltd | Construction | 2023 |
| South East Windscreen Repairs Ltd | Wholesale & retail | 2021 |
| South Tasks Ltd | Construction | 2026 |
| South-East Technical Services Limited | Professional & scientific | 2005 |
| Southdown Contractors Limited | Construction | 2003 |
| Southern Access Solutions Limited | Construction | 2002 |
| Southern Car Scrap Limited | Wholesale & retail | 2016 |
| Southern Counties Caring Ltd | Health & social care | 2019 |
| Southern Counties Ice Cream Ltd | Wholesale & retail | 2025 |
| Southern Cross Holdings Ltd | Financial services | 2026 |
| Southern Garage Doors Limited | Construction | 2021 |
| Southern Hiab Services Ltd | Transport & logistics | 2011 |
| Southern Optical Services Limited | Health & social care | 2006 |
| Southern Partnership Services Limited | Administrative & support | 2010 |
| Southern Securities PLC | Professional & scientific | 2009 |
| Southern Sheeting Properties Ltd | Real estate | 2024 |
| Southern Sheeting Supplies Ltd | Construction | 2013 |
| Southern Solar Limited | Construction | 2023 |
| Southern Travel Solutions Ltd | Transport & logistics | 2020 |
| Southern UK Communications Limited | Information & communication | 2019 |
| Southgate Fish & Chips Ltd | Hospitality | 2022 |
| Southgate Maisonettes (68 and 69) Limited | Households | 2005 |
| Southood Healthcare Limited | Health & social care | 2022 |
| Southsea Dental Care Limited | Health & social care | 2008 |
| Southside Events Ltd | Administrative & support | 2025 |
| Sovereign Properties (Sussex) Limited | Real estate | 2022 |
| Soyom Limited | Health & social care | 2019 |
| SP Surveying Sussex Ltd | Professional & scientific | 2021 |
| Space City Drop Ltd | Wholesale & retail | 2022 |
| Space DBM Ltd | Construction | 2018 |
| Space Works (South East) Ltd | Real estate | 2020 |
| Space Works Consultancy Ltd | Professional & scientific | 2020 |
| Spacetitle Limited | Manufacturing | 1990 |
| Sparbaco Limited | Professional & scientific | 2024 |
| Sparesmaster Limited | Wholesale & retail | 1986 |
| Sparkle Carpet Cleaning & Upholstery Cleaning Crawley & Horley Limited | Administrative & support | 2025 |
| Sparrow Cleaning Limited | Administrative & support | 2024 |
| Sparrow Home Care Limited | Health & social care | 2026 |
| Sparrow Home Cleaning Limited | Administrative & support | 2026 |
| Sparrow Medical Sales Limited | Manufacturing | 2023 |
| Spars Mart Ltd | Wholesale & retail | 2023 |
| Specialised Interiors Limited | Construction | 2015 |
| Specialist Engineering Solutions Limited | Professional & scientific | 2000 |
| Speech Computing Ltd | Information & communication | 2020 |
| Speed Star Logistics Limited | Transport & logistics | 2022 |
| Speed Star Ltd | Transport & logistics | 2019 |
| Speed Trading Ltd | Transport & logistics | 2015 |
| Speedbird Care Limited | Administrative & support | 2024 |
| Speedwell Investments Limited | Real estate | 1948 |
| Spgtv Limited | Information & communication | 1993 |
| Spice Caterers Ltd | Other services | 2022 |
| Spicy Cafe Ltd | Hospitality | 2022 |
| Spikex Ltd | Construction | 2023 |
| Spirent (Overseas) Limited | Professional & scientific | 2000 |
| Spirent Capital Limited | Extraterritorial | 1999 |
| Spirent Financial Limited | Professional & scientific | 1999 |
| Spirent Holdings Limited | Extraterritorial | 1997 |
| Spirent Investment Limited | Professional & scientific | 2000 |
| Spirent Limited | Extraterritorial | 1962 |
| Spirent Sharesave Trust Limited | Professional & scientific | 1997 |
| Spirent Systems Limited | Extraterritorial | 1991 |
| Splitpics Limited | Information & communication | 2019 |
| Sport Genius Limited | Other services | 2023 |
| Sport Genius Skincare Limited | Other services | 2023 |
| Sportickality Ltd | Administrative & support | 2014 |
| Sports Education and Training Limited | Arts & recreation | 2015 |
| Sports Technology Limited | Administrative & support | 2011 |
| Sportsliner Limited | Transport & logistics | 2008 |
| Sportway UK Ltd | Information & communication | 2020 |
| Spotless by Stephanie Ltd | Other services | 2019 |
| Spotted Logistics Ltd | Transport & logistics | 2025 |
| SPQR1927 Ltd | Transport & logistics | 2019 |
| Sprg Ltd | Administrative & support | 2025 |
| Springfield Rental Holdings Limited | Real estate | 2019 |
| SPS Assets Ltd | Real estate | 2021 |
| SPS Quality Ltd | Wholesale & retail | 2020 |
| SPT Capital Ltd | Financial services | 2024 |
| Spuddy Buddy Ltd | Hospitality | 2025 |
| SPV Emro Investments 1 Ltd | Financial services | 2025 |
| Spyro Limited | Health & social care | 2016 |
| Sqair Consultancy Limited | Transport & logistics | 2024 |
| Squashlete Ltd | Arts & recreation | 2020 |
| SR Brickwork Contractors Ltd | Construction | 2020 |
| SR James Ltd | Construction | 2015 |
| SR. Rani Ltd | Wholesale & retail | 2025 |
| Sred Properties Limited | Households | 2026 |
| SRH BIZ Hub Ltd | Wholesale & retail | 2025 |
| SRI Express Removals and Storage Limited | Transport & logistics | 2025 |
| SRI Lankan Muslim Diaspora Initiative United Kingdom - Slmdi UK | Health & social care | 2017 |
| SRJ Groundworks Ltd | Construction | 2021 |
| SRS YP Consultancy Limited | Professional & scientific | 2018 |
| SS Executive Chauffeur Ltd | Transport & logistics | 2023 |
| Ssoula Carpentry Ltd | Construction | 2024 |
| SSP Equestrian Limited | Education | 2019 |
| Ssranjhaxpress Limited | Wholesale & retail | 2025 |
| SST Plumbing and Heating Ltd | Construction | 2025 |