| Saff's Services Ltd | Transport & logistics | 2013 |
| Saffron Ddraig Ltd | Hospitality | 2025 |
| Saffron ST Davids Limited | Hospitality | 2017 |
| Saftrad Limited | Wholesale & retail | 2018 |
| Saftrad Property Limited | Construction | 2020 |
| SAH Electrical (South Wales) Limited | Construction | 2018 |
| Saigal Estates Ltd | Wholesale & retail | 2023 |
| Saigon 18 Limited | Hospitality | 2025 |
| Saikou Skincare Limited | Manufacturing | 2022 |
| Saini Delivery Services Ltd | Transport & logistics | 2025 |
| Sainsbury & Sainsbury Ltd | Professional & scientific | 2026 |
| Saint Camillus Limited | Health & social care | 1985 |
| Saint Gerard Holdings Limited | Real estate | 1987 |
| Saint-Hugo Cardiff Limited | Wholesale & retail | 2026 |
| Saint-Hugo Ltd | Wholesale & retail | 2024 |
| Saint-Hugo Swansea Limited | Wholesale & retail | 2026 |
| Sainy's Recipes Ltd | Hospitality | 2024 |
| SAJ Developments Ltd | Information & communication | 2022 |
| Sak's Cuts Limited | Other services | 2025 |
| SAL Trades Ltd | Wholesale & retail | 2024 |
| Sal's Savories Ltd | Manufacturing | 2023 |
| Salamat Consultancy Limited | Health & social care | 2021 |
| Salamat Limited | Health & social care | 2014 |
| Salamco Limited | Real estate | 2021 |
| Salb Food Ltd | Hospitality | 2026 |
| Sales GP Limited | Administrative & support | 2011 |
| Salis Electrical Limited | Construction | 2017 |
| Sally Beauty Centre Ltd | Other services | 2024 |
| Sally's Smiles Ltd | Health & social care | 2019 |
| Salt & Light Community CIC | Education | 2021 |
| Salt and Light Retreat Ltd | Education | 2017 |
| Salt Film Releasing Limited | Information & communication | 2017 |
| Salt House Media Ltd | Information & communication | 2024 |
| Salt Mango Tree Restaurant Ltd | Hospitality | 2024 |
| Salt White Studio Limited | Professional & scientific | 2017 |
| Saltskin Ltd | Wholesale & retail | 2022 |
| Salty Hookers Ltd | Agriculture & fishing | 2021 |
| Salty Investments Ltd | Real estate | 2024 |
| Salubrious Kitchen OPS Ltd | Hospitality | 2022 |
| Salus Care Wales Ltd | Health & social care | 2019 |
| SAM Barber Swansea Ltd | Other services | 2022 |
| SAM Harper Creative Limited | Arts & recreation | 2026 |
| SAM Recovery Swansea C.I.C. | Health & social care | 2020 |
| SAM Sharp Barber Ltd | Other services | 2024 |
| SAM Webborn Osteopathy Limited | Health & social care | 2018 |
| Samantha K'S Ltd | Wholesale & retail | 2007 |
| Samatek Ltd | Manufacturing | 2016 |
| Samatrix Group Limited | Construction | 2016 |
| Samatrix Limited | Manufacturing | 2001 |
| Samawi London Limited | Wholesale & retail | 2024 |
| Sambuck Holdings Limited | Real estate | 2026 |
| Samer Ltd | Hospitality | 2025 |
| Samlet Springs Management (NO.1) Limited | Real estate | 1992 |
| Samlet Springs Management (NO.2) Limited | Households | 1993 |
| Samphire Hair Design Ltd | Other services | 2013 |
| Sams Barbers Gorseinon Ltd | Other services | 2019 |
| Samuel Care Homes Ltd | Real estate | 2024 |
| Sand Bunker Limited | Hospitality | 2021 |
| Sand Mould Solutions Limited | Professional & scientific | 2011 |
| Sanders Cabs Limited | Transport & logistics | 2019 |
| Sandfields Properties Ltd | Hospitality | 2017 |
| Sandfish Software Ltd | Information & communication | 2002 |
| Sandhu Cheema Ltd | Hospitality | 2019 |
| Sandhu in Brean Ltd | Hospitality | 2015 |
| Sandles Property Developments Limited | Construction | 2025 |
| Sandles Wealth Management Limited | Financial services | 2005 |
| Sands and Carter Ltd | Professional & scientific | 2015 |
| Sands Cymru (Harm Reduction) Ltd. | Health & social care | 2010 |
| Sandtsolutionservice Ltd Ltd | Health & social care | 2025 |
| Sanktuary Education Limited | Education | 2018 |
| Sanmarley Limited | Other services | 2016 |
| Sansha (UK) Limited | Wholesale & retail | 1993 |
| Sansum Properties Ltd | Real estate | 2022 |
| Santa Isabel Property Management Ltd | Real estate | 2022 |
| Sanuent Limited | Health & social care | 2014 |
| Sanuent Properties Limited | Households | 2023 |
| SAP Developments Limited | Real estate | 2018 |
| SAP Property Developments and Investments Limited | Construction | 2010 |
| Sapan Limited | Hospitality | 2002 |
| Sapien Nutritionals Limited | Administrative & support | 2007 |
| Sapphire Care Agency Limited | Information & communication | 2024 |
| Sapphire Care Plus Limited | Health & social care | 2015 |
| Sapphire Windows & Doors Limited | Manufacturing | 2023 |
| Saproco UK Limited | Real estate | 2018 |
| Sara Caroline Floral Design Limited | Wholesale & retail | 2016 |
| Sarah Cole Consultancy Limited | Professional & scientific | 2009 |
| Sarah Supreme Limited | Health & social care | 2022 |
| Saren Travel DMC Limited | Transport & logistics | 2023 |
| Saren Travel Group - Educational Experiences Ltd | Administrative & support | 2025 |
| Saren Travel Group Ltd | Administrative & support | 2021 |
| Saren Travel Group Tour Wholesale Ltd | Administrative & support | 2025 |
| Sargent & Family Limited | Real estate | 2022 |
| Sargent Financial Planning Ltd | Financial services | 2024 |
| Sarlou Court Management Company Limited | Real estate | 1986 |
| Sarn Limited | Real estate | 2021 |
| Sarno Square (Abergavenny) Limited | Households | 2019 |
| Sarwed Properties Limited | Real estate | 1947 |
| Sash & Co Jewellery Ltd | Wholesale & retail | 2026 |
| Satin and Gold Ltd | Information & communication | 2016 |
| Satnamsinghtransltd Limited | Transport & logistics | 2025 |