| S.Davies Electrical & Building Services Ltd | Construction | 2011 |
| S.F. Electrical Limited | Construction | 2005 |
| S.G. Restaurants Limited | Hospitality | 1998 |
| S.G. Services Group Limited | Administrative & support | 2015 |
| S.G.D. Security Ltd. | Construction | 1998 |
| S.Galninchester Trading Ltd | Wholesale & retail | 2025 |
| S.H.G Estates Limited | Construction | 1999 |
| S.I. Automotive Services Ltd | Wholesale & retail | 2020 |
| S.I.A Developments Ltd | Hospitality | 2015 |
| S.J.Dannatt Logistics Limited | Transport & logistics | 2013 |
| S.J.Farmer(Long Eaton)Limited | Wholesale & retail | 1957 |
| S.K.M. Recycling Services Ltd | Water & waste | 2018 |
| S.L.Uminga Company Ltd | Health & social care | 2023 |
| S.M.A.K.E Limited | Health & social care | 2019 |
| S.O.E Consultancy Limited | Information & communication | 2019 |
| S.P.A.F. Collective Ltd | Information & communication | 2021 |
| S.P.A.K. DR. Springer Petersen Altmann UND Kollegen Kanzlei Limited | Administrative & support | 2013 |
| S.R. Holdco (UK) Limited | Financial services | 2021 |
| S.R.A. & SON Ltd | Construction | 2018 |
| S.R.James Rail Welding Limited | Construction | 2020 |
| S.R.T. (Cardiff) Ltd | Construction | 2017 |
| S.U.D Services Cardiff Ltd | Water & waste | 2022 |
| S.W.Oldroyd & Sons Limited | Real estate | 1962 |
| S/E Afrika Limited | Information & communication | 2017 |
| S/Y Kemmerer LLP | | 2021 |
| S1 Impact Trading Limited | Hospitality | 2021 |
| S2 Lifestyle Management Ltd | Professional & scientific | 2014 |
| S22 Trading Ltd | Wholesale & retail | 2023 |
| S2D Platform Ltd | Information & communication | 2025 |
| S3 Advertising Limited | Professional & scientific | 2019 |
| S39 Ltd | Wholesale & retail | 2025 |
| S3C Ltd. | Professional & scientific | 2017 |
| S4 Cleaning and Logistics Ltd | Transport & logistics | 2024 |
| S4 Services Ltd | Wholesale & retail | 2026 |
| S6 Official Ltd | Wholesale & retail | 2025 |
| S8080 EOT Limited | Professional & scientific | 2025 |
| S88 Property Ltd | Real estate | 2025 |
| SA Accountants Private Ltd | Professional & scientific | 2023 |
| SA Asset Investment Group Ltd | Real estate | 2026 |
| SA Business Psychology Ltd | Professional & scientific | 2016 |
| SA Cardiff Properties Limited | Real estate | 2018 |
| SA Family Property Limited | Real estate | 2025 |
| SA Gelato Limited | Hospitality | 2016 |
| SA Greenlance Ltd | Wholesale & retail | 2019 |
| SA Group Private Ltd | Financial services | 2023 |
| SA Marketing & Communications Ltd | Financial services | 2015 |
| SA Rental Ltd | Administrative & support | 2019 |
| SA Solution Hub Ltd | Wholesale & retail | 2026 |
| SA Sparkles Ltd | Households | 2025 |
| SA Surgical Services Ltd | Health & social care | 2020 |
| SA Technologies Ltd | Professional & scientific | 2022 |
| SA1 Carpet & Flooring Ltd | Wholesale & retail | 2025 |
| SA26 Property Ltd | Real estate | 2021 |
| SA3 Practice Limited | Extraterritorial | 2019 |
| SAA Electrical Service Limited | Construction | 2014 |
| Saab Shrestha Investments Ltd | Real estate | 2024 |
| Saabstyle Swedish Service Centre Limited | Wholesale & retail | 1998 |
| Saad Belarbi Ltd | Wholesale & retail | 2025 |
| Saad Ecom Ltd | Wholesale & retail | 2026 |
| Saad Karim Ltd | Professional & scientific | 2019 |
| SAADKHAN14 Ltd | Health & social care | 2024 |
| Saah Ltd | Professional & scientific | 2008 |
| Saaim Ltd | Wholesale & retail | 2021 |
| Saakoon Limited | Arts & recreation | 2016 |
| Saanitha Imports and Exports Limited | Wholesale & retail | 2025 |
| Saanjh Ltd | Wholesale & retail | 2025 |
| Saara & Co Healthcare Ltd | Health & social care | 2025 |
| Saarc Skills Ltd | Professional & scientific | 2023 |
| Saark Limited | Health & social care | 2018 |
| Saarthi Enterprises Ltd | Transport & logistics | 2025 |
| Saas Enterprise Ltd | Information & communication | 2018 |
| Saaspot Ltd | Information & communication | 2025 |
| Saasy Limited | Information & communication | 2026 |
| Saathi Law Chambers Ltd | Professional & scientific | 2021 |
| SAB Cardiff Ltd | Hospitality | 2025 |
| SAB Rail Limited | Construction | 2018 |
| Saba Knights Ltd | Real estate | 2024 |
| Sabah Pharma Limited | Wholesale & retail | 2025 |
| Sabaton PC | | 2017 |
| Sabaz ALI Ltd | Wholesale & retail | 2025 |
| Sabery Properties Ltd | Real estate | 2024 |
| Sabge Limited | Health & social care | 2014 |
| Sabge Publishing Ltd | Wholesale & retail | 2019 |
| Sabinaite Contracting Ltd | Transport & logistics | 2016 |
| Sabino & Sabine Enterprises Limited | Other services | 2017 |
| Sabir ALI Empire Ltd | Wholesale & retail | 2025 |
| Sables Healthcare Limited | Health & social care | 2018 |
| Sabor DE Italia Limited | Wholesale & retail | 2021 |
| Sabr Works Ltd | Wholesale & retail | 2025 |
| Sabre Financial Services Ltd | Financial services | 2018 |
| Sabre Graphics Ltd | Wholesale & retail | 2019 |
| Sabrelake Ltd | Professional & scientific | 2019 |
| Sabrhero Ltd | Wholesale & retail | 2022 |
| Sabs (Cardiff) Limited | Real estate | 2016 |
| Sacartoc | Professional & scientific | 2024 |
| Saccounts Limited | Professional & scientific | 2015 |
| Saccs Event Ltd | Hospitality | 2025 |
| Sach Chemists Limited | Health & social care | 2003 |
| Sachmad International Limited | Wholesale & retail | 2016 |
| Sachville Court Limited | Households | 2015 |