| Stainless Services Limited | Manufacturing | 1982 |
| Stainless Special Projects Ltd | Information & communication | 2017 |
| Stainless Steel Catering Fabrications Limited | Manufacturing | 2016 |
| Stairway Joinery Limited | Manufacturing | 1988 |
| Stamy Holdings Limited | Administrative & support | 2025 |
| Stan Evans Farms Limited | Agriculture & fishing | 2015 |
| Stan Evans Limited | Financial services | 2015 |
| Stanco Display Ltd | Administrative & support | 2014 |
| Stancombe House Management Company Limited | Real estate | 1988 |
| Standard Signs & Traffic Systems Limited | Manufacturing | 1983 |
| Standard Signs Engineering Ltd | Professional & scientific | 2025 |
| Standard Signs Systems Limited | Financial services | 2009 |
| Standardbred GB Limited | Agriculture & fishing | 2020 |
| Standley Babs Service Ltd | Health & social care | 2026 |
| Stanley Builders Limited | Construction | 2017 |
| Stanley Kitchens Limited | Construction | 2015 |
| Staplers Court (Management) Company Limited | Households | 1969 |
| Star Coach Travel Ltd | Transport & logistics | 2022 |
| Starfirm Properties Limited | Real estate | 2022 |
| Stark Legal Ltd | Professional & scientific | 2025 |
| Starlight Academy Limited | Education | 2022 |
| Starplast UK Ltd | Manufacturing | 2025 |
| Stately Leisure Limited | Arts & recreation | 2022 |
| Stately-Albion Limited | Manufacturing | 1964 |
| Statera Initiative Limited | Health & social care | 2019 |
| Station Court (Shanklin) Management Company Limited | Households | 1990 |
| Stavex Ltd | Construction | 2024 |
| Stay Balanced Ltd | Hospitality | 2021 |
| Stayma Ltd | Hospitality | 2021 |
| Stayunico Ltd | Construction | 2016 |
| STB Investments Limited | Construction | 2005 |
| Stcm Ltd | Wholesale & retail | 2022 |
| Stdave Ltd | Professional & scientific | 2026 |
| Steadyit Ltd | Information & communication | 2026 |
| Steam Island IOW Limited | Wholesale & retail | 2017 |
| Steam Shed Limited | Extraterritorial | 2014 |
| Steampunk IOW Limited | Wholesale & retail | 2017 |
| Steaua 25 Ltd | Construction | 2025 |
| Stedman Bros. (Events) Limited | Wholesale & retail | 1939 |
| Steed Steele Limited | Wholesale & retail | 2015 |
| Steele Industries Limited | Manufacturing | 2011 |
| Steelhouse Festival Limited | Arts & recreation | 2015 |
| Stellies Change Management Ltd | Professional & scientific | 2023 |
| Stelvio Securities Limited | Professional & scientific | 1979 |
| Step Point Limited | Health & social care | 2015 |
| Stephen Belshaw Legal Ltd | Professional & scientific | 2019 |
| Stephen Peachey Limited | Other services | 2011 |
| Stephens Engineering Group Ltd | Construction | 2025 |
| Stephenson's Rentals Ltd | Real estate | 2025 |
| Stepping Stone Cardiff Two Ltd | Hospitality | 2025 |
| Stepping Stone Newport Ltd | Hospitality | 2022 |
| Sterile Service Developments Limited | Health & social care | 2017 |
| Sterling Clean Solutions Ltd | Administrative & support | 2025 |
| Sterling Drive Motors Ltd | Wholesale & retail | 2026 |
| Steve Clements Consulting Ltd | Professional & scientific | 2014 |
| Steve Howells Engineering Ltd | Professional & scientific | 2019 |
| Steve Hughes Haulage Limited | Transport & logistics | 2003 |
| Steve Means Performance Limited | Arts & recreation | 2025 |
| Steve Norton Carpentry Limited | Manufacturing | 2022 |
| Steve Parfitt Builders Ltd | Construction | 2026 |
| Steve Payne Props Ltd | Information & communication | 2015 |
| Steve Rogers Services Limited | Administrative & support | 2020 |
| Steve Truman Golf Ltd | Arts & recreation | 2015 |
| Steve Williams & SON Limited | Construction | 2018 |
| Steve Williams Car Sales Limited | Wholesale & retail | 2003 |
| Steve's 24/7 Equities Trading and Investments Ltd | Financial services | 2022 |
| Steven Davies Properties Ltd | Real estate | 2024 |
| Steven Davies Property Living Ltd | Real estate | 2025 |
| Steven Deliveries Ltd | Other services | 2025 |
| Stevenson Medical Ltd | Health & social care | 2022 |
| Sticky INK Studios Ltd | Manufacturing | 2013 |
| Stirling Silver Ltd | Water & waste | 2022 |
| Stitch in Time NPT Ltd | Other services | 2025 |
| STM 3 (Newport) Ltd | Hospitality | 2015 |
| Stmc Consulting Ltd | Professional & scientific | 2024 |
| STN Painting and Decorating Limited | Administrative & support | 2025 |
| STO Logistics Ltd | Transport & logistics | 2016 |
| Stoc (Pembs) Ltd | Hospitality | 2026 |
| Stock I T Limited | Information & communication | 2014 |
| Stockton Energy Limited | Energy | 2014 |
| Stockwood Property Management Ltd | Real estate | 2024 |
| Stoker Holdings Limited | Real estate | 2016 |
| Stone Bear Capital Limited | Professional & scientific | 2019 |
| Stone Farm Riding Limited | Arts & recreation | 2014 |
| STONE2010 Limited | Other services | 2010 |
| Stonebel Ltd | Real estate | 2023 |
| Stonebow Developments Limited | Real estate | 2018 |
| Stonecore Directors Limited | Professional & scientific | 2003 |
| Stonecore Secretaries Limited | Professional & scientific | 2003 |
| Stonefield Construction Ltd | Construction | 2026 |
| Stonehaus Contracts Ltd | Wholesale & retail | 2018 |
| Stonepeak Properties Ltd | Real estate | 2026 |
| Stonewood Gate (Management) Limited | Extraterritorial | 2011 |
| Stor.Ree Ltd | Manufacturing | 2026 |
| Storage & More Caerleon Limited | Administrative & support | 2025 |
| Storage & More Ltd | Administrative & support | 2025 |
| Storage Giant Limited | Administrative & support | 2003 |
| Storage Solutions 360 Ltd | Administrative & support | 2025 |
| Store Your Sins Ltd | Wholesale & retail | 2022 |
| Stories From Limited | Other services | 2020 |