| Scott's Apartment Ltd | Real estate | 2024 |
| Scottmed Distribution (UK) Ltd | Wholesale & retail | 2023 |
| Scott’S Bars and Kitchens Limited | Hospitality | 2025 |
| Scoupy Ltd | Wholesale & retail | 2021 |
| Scoutscapital Limited | Information & communication | 2023 |
| Scpmerce Ltd | Wholesale & retail | 2025 |
| SCR Commercial Estates Ltd | Real estate | 2021 |
| Scramb PS Ltd | Administrative & support | 2017 |
| Scrapdoc Limited | Water & waste | 2025 |
| Scrapmetal London Limited | Water & waste | 2026 |
| Scratch FIX Body Repairs Limited | Wholesale & retail | 2017 |
| Screamania Promotions Limited | Professional & scientific | 2003 |
| Screaming Pictures Ltd | Information & communication | 2011 |
| Screen Alliance for Wales Limited | Information & communication | 2017 |
| Screen Moguls Ltd | Information & communication | 2018 |
| Screenher Ltd | Information & communication | 2025 |
| Screensight Ltd | Information & communication | 2020 |
| Screentent Limited | Extraterritorial | 2006 |
| Screwball Ltd | Real estate | 2019 |
| Scribble Investments Limited | Information & communication | 2010 |
| Scrollstop Media Ltd | Wholesale & retail | 2026 |
| Scrooge the Board Game LLP | | 2017 |
| Scrsdwr Mart Ltd | Wholesale & retail | 2025 |
| Scrubd Ltd | Wholesale & retail | 2016 |
| Scruffy Dog Public Relations Limited | Professional & scientific | 2009 |
| Scruffy Dogs Services Ltd | Wholesale & retail | 2021 |
| Scruffyhead Ltd | Information & communication | 2012 |
| Scrum Recap Limited | Manufacturing | 2024 |
| Scrum-Q Training Ltd | Education | 2015 |
| Scrumptons Limited | Manufacturing | 2015 |
| SCS Engineering Limited | Professional & scientific | 2017 |
| SCS Secure Clean Solutions Ltd | Financial services | 2025 |
| SCS Trading Europe Ltd | Wholesale & retail | 2022 |
| Scss (Exeter) Limited | Manufacturing | 1994 |
| Scth Cardiff Ltd | Hospitality | 2026 |
| Scto Partners Limited | Information & communication | 2025 |
| Scuderia DI Vincitori Limited | Arts & recreation | 2020 |
| Scuffz Wheelz Limited | Wholesale & retail | 2016 |
| Scurry Productions Limited | Information & communication | 2022 |
| Scutarii Intelligence Ltd | Professional & scientific | 2020 |
| Scuttlebutt Limited | Manufacturing | 2025 |
| Scylla Social Ltd | Professional & scientific | 2021 |
| SD Building Services Cardiff Limited | Construction | 2017 |
| SD Kuntal Gynaecologists Ltd | Health & social care | 2025 |
| SD Property Group Limited | Real estate | 2019 |
| SDK Management Limited | Professional & scientific | 2020 |
| Sdkuk Limited | Administrative & support | 2023 |
| Sdlt Refunds Limited | Professional & scientific | 2012 |
| SDM Glass Limited | Manufacturing | 2014 |
| SDM Group Services Ltd | Professional & scientific | 2025 |
| SDN (Repairs) Limited | Wholesale & retail | 2019 |
| SDP Accountants Ltd | Professional & scientific | 2024 |
| SDP Advisors Limited | Professional & scientific | 2024 |
| Sdpa Cardiff Ltd | Administrative & support | 2024 |
| Sdpg Ltd | Financial services | 2019 |
| SDR IT Consulting Limited | Information & communication | 2014 |
| SDS Bookkeeping Limited | Professional & scientific | 2022 |
| SDS Property Limited | Real estate | 2019 |
| SDS Swiss UK Ltd | Health & social care | 2017 |
| SDS303 Limited | Wholesale & retail | 2021 |
| SDT Property Services Ltd | Construction | 2019 |
| SDW Global Services Limited | Professional & scientific | 2015 |
| Sdwaldron Ltd | Real estate | 2019 |
| SDX Limited | Financial services | 2022 |
| Se-Sa Global Ltd | Wholesale & retail | 2025 |
| SE15 Properties Limited | Real estate | 2010 |
| SE7EN Academy Ltd | Professional & scientific | 2025 |
| Sea Change Counselling Limited | Health & social care | 2024 |
| Sea Concierge Limited | Manufacturing | 2025 |
| Sea Food Media Group Limited | Professional & scientific | 2021 |
| Sea Front Fitness Ltd | Other services | 2026 |
| Sea Link Group Co., Ltd | Extraterritorial | 2019 |
| Sea Marine Services Limited | Other services | 2015 |
| Sea Point Freight Management Ltd | Transport & logistics | 2026 |
| Sea Sunset Ltd | Arts & recreation | 2016 |
| Sea View Management Company Limited | Households | 1961 |
| Seabank Court Management Limited | Households | 1985 |
| Seabourne Global Cargo Ltd | Transport & logistics | 2019 |
| Seacoral Ltd | Administrative & support | 2019 |
| Seacure Group Ltd | Administrative & support | 2024 |
| Seadag Property Ventures Ltd | Construction | 2019 |
| Seafood Boss Ltd | Hospitality | 2020 |
| Seafood Galore NMP Ltd | Hospitality | 2022 |
| Seagall Limited | Real estate | 2008 |
| Seager Drive Freehold Company Ltd | Real estate | 2012 |
| Seal & Shield Ltd | Administrative & support | 2026 |
| Seal Bay Property Group Ltd | Real estate | 2025 |
| Seal Integrated Systems Ltd | Administrative & support | 2013 |
| Seal Security UK Limited | Public administration | 2006 |
| Sealmasters Holdings Ltd | Financial services | 2025 |
| Sealmasters Limited | Wholesale & retail | 1989 |
| Sealyham Activity Centre Limited | Hospitality | 1986 |
| Sean Bishop Building Limited | Construction | 2017 |
| Sean Rees Ltd | Professional & scientific | 2020 |
| Seanks Properties Ltd | Real estate | 2021 |
| Seapoint (Barry) Management Company Limited | Households | 1981 |
| Seapoint Residents Association Limited | Households | 1975 |
| Seaport Environmental Limited | Water & waste | 2001 |
| Search Airport Parking Ltd | Transport & logistics | 2019 |
| Search Click Drive Ltd | Information & communication | 2018 |