| Spirit of Wales Ltd | Manufacturing | 2020 |
| Spiritlevel Ltd | Professional & scientific | 2025 |
| SPK Composites Ltd | Manufacturing | 2019 |
| SPL Management Services Limited | Professional & scientific | 2021 |
| Splendid Smells Limited | Manufacturing | 2022 |
| SPM (UK) Limited | Manufacturing | 2006 |
| Spme Limited | Extraterritorial | 2013 |
| Sporting Chance Newport Community Interest Company | Education | 2020 |
| Sporting Chance School Limited | Education | 2023 |
| Sporting Wales Limited | Professional & scientific | 2000 |
| Sports & Prestige Automotive Ltd | Wholesale & retail | 2021 |
| Sports Performance Centre IOW Ltd | Arts & recreation | 2023 |
| Sports Surface Technologys Ltd | Extraterritorial | 2012 |
| SPORTS56 Ltd | Wholesale & retail | 2026 |
| Spot on Clean Ltd | Construction | 2019 |
| Spotlight (IOW) Limited | Arts & recreation | 2010 |
| SPR Property Solutions Ltd | Real estate | 2025 |
| SPR Scaffolding IOW Limited | Construction | 2022 |
| Sprake Developments Limited | Construction | 1994 |
| Spratt Group Ltd | Financial services | 2025 |
| Spratt Trading Ltd | Transport & logistics | 2025 |
| Spray - ME Limited | Construction | 2022 |
| Sprayfoam Eco Ltd | Construction | 2014 |
| Spraytek Solutions Ltd | Wholesale & retail | 2026 |
| Spraytex Systems Limited | Construction | 2011 |
| Spraywash Limited | Other services | 1987 |
| Spring Inn Ltd | Hospitality | 2025 |
| Springfield Court (Seaview Isle of Wight) Management Company Limited | Households | 2004 |
| Springs Estate Ltd | Real estate | 2023 |
| Springvale (South Wales) Limited | Administrative & support | 2025 |
| Springvale (Weatherproofing) Limited | Construction | 1978 |
| Sprinkles Desserts Ltd | Hospitality | 2022 |
| Spudds Kitchen Limited | Hospitality | 2025 |
| Spytty Lane Flats (Management) Limited | Households | 1982 |
| Square Compass Consulting Ltd | Professional & scientific | 2025 |
| Square Scaffolding Limited | Other services | 2021 |
| Square SIX Limited | Real estate | 2009 |
| Squared Developments Ltd | Construction | 2019 |
| Squid Properties Limited | Households | 2023 |
| Squillace Company Ltd | Construction | 2022 |
| Squire Cars Ltd | Wholesale & retail | 2002 |
| Squires Family Pubs Limited | Hospitality | 2026 |
| SR Rosh Holdings Limited | Financial services | 2025 |
| SR Wholesales Limited | Wholesale & retail | 2025 |
| SRC Concepts Ltd | Information & communication | 2011 |
| Sreeramshi Ltd | Information & communication | 2020 |
| SRG Building Limited | Construction | 2024 |
| SRI Sumukha Property Limited | Real estate | 2020 |
| Srisaisum Limited | Health & social care | 2017 |
| SRJ & JG Partnership Limited | Financial services | 2016 |
| SRK Carpentry & Building Services Ltd | Construction | 2011 |
| SRK Consulting (Kazakhstan) Limited | Professional & scientific | 2010 |
| SRK Consulting (Russia) Nominee Company Limited | Professional & scientific | 2008 |
| SRK Exploration Services Nominee Company Limited | Financial services | 2011 |
| SRK Leisure Limited | Hospitality | 2024 |
| SRM Communications Limited | Arts & recreation | 2011 |
| SS Electrofusion Ltd | Wholesale & retail | 2025 |
| SS Recruitment & Payroll Ltd | Administrative & support | 2024 |
| SS5 Promotions Limited | Arts & recreation | 2022 |
| SS8 Promotions Ltd | Arts & recreation | 2021 |
| SS8 Properties Ltd | Real estate | 2022 |
| SSJ Contractors Limited | Construction | 1999 |
| SSK Health Ltd | Administrative & support | 2023 |
| Sslgj Ltd | Real estate | 2017 |
| SSR Empire Ltd | Real estate | 2025 |
| SSR Retail Ltd | Wholesale & retail | 2024 |
| ST Albans Property Group Ltd | Real estate | 2016 |
| ST Andrews Court (Freshwater) Management Company Limited | Households | 2004 |
| ST Andrews Court (Lake) Limited | Households | 2007 |
| ST Basil's Rise (Management Company) Limited | Real estate | 2004 |
| ST Brides Holdings Limited | Financial services | 2026 |
| ST Catherine's John Street Limited | Households | 2022 |
| ST Catherines Chartering Services Ltd | Transport & logistics | 2014 |
| ST Cecilia (Newport) RTM Company Limited | Households | 2025 |
| ST David's Trading Limited | Wholesale & retail | 2006 |
| ST George's Physiotherapy Limited | Health & social care | 2002 |
| ST Handyman Services Ltd | Construction | 2026 |
| ST Helens Service Station (Isle of Wight) Limited | Wholesale & retail | 2003 |
| ST Johns Court Sandown (Management) Ltd | Households | 2024 |
| ST Joseph's Independent Hospital Limited | Health & social care | 2019 |
| ST Maurs Estate Limited | Real estate | 2013 |
| ST Nicholas Place (Newport) Management Limited | Households | 2016 |
| ST Thomas House Limited | Real estate | 2013 |
| ST Wilfrids (Isle of Wight) Management Company Limited | Households | 2010 |
| ST Woolos Barbers Limited | Other services | 2025 |
| ST Woolos Complete Care Ltd | Health & social care | 2021 |
| St-Four Limited | Information & communication | 2005 |
| ST. Brides Investments Limited | Construction | 1995 |
| ST. David's Foundation Hospice Care | Health & social care | 1992 |
| ST. James House (Leeds) Limited | Extraterritorial | 2001 |
| ST. Joseph's Lodge Management Company Limited | Households | 1984 |
| St.Mary's View (Newport Isle of Wight) Management Company Limited | Extraterritorial | 2004 |
| St.Maur Management Limited | Households | 1986 |
| ST1213 Ltd | Arts & recreation | 2024 |
| Staff 247 Limited | Administrative & support | 2008 |
| Stag and Canary Property Ltd | Real estate | 2024 |
| Stage Mania Ltd | Arts & recreation | 2025 |
| Stageone Projects Ltd | Wholesale & retail | 2025 |
| Stainless Games Limited | Information & communication | 2001 |
| Stainless Services (Holdings) Limited | Financial services | 2017 |