| 1 Rosebery Place Management Company Limited | Households | 2002 |
| 102WR (Penarth) Management Company Limited | Households | 2021 |
| 11 A/B Cliff Street Ltd | Professional & scientific | 2012 |
| 11 Knights Walk RTM Company Limited | Real estate | 2014 |
| 1159 Marketing Ltd | Professional & scientific | 2016 |
| 12 Royal Buildings Management Company Limited | Households | 2006 |
| 121 Consult Ltd | Education | 2017 |
| 14 Lord ST. Management Company Limited | Real estate | 2004 |
| 145 Windsor Road (Penarth) Management Company Limited | Real estate | 2004 |
| 160 Penarth Apartments Management Limited | Hospitality | 2013 |
| 165-171 Redlands Road Management Company Limited | Professional & scientific | 1998 |
| 18 Silver Street Ltd | Real estate | 2025 |
| 1ST Communications Limited | Construction | 2007 |
| 1ST for Bookkeeping Ltd | Professional & scientific | 2022 |
| 1ST Life Group Limited | Professional & scientific | 2024 |
| 2 Church Avenue Penarth Management Company Limited | Hospitality | 2003 |
| 2020 Certification Limited | Manufacturing | 2018 |
| 222 Property Investments Ltd | Real estate | 2020 |
| 227 QTR Ltd | Real estate | 2009 |
| 23 Property Management Limited | Households | 2024 |
| 23 Victoria Square (Penarth) Freehold Company Limited | Households | 2025 |
| 24 Victoria Square (Penarth) Freehold Company Limited | Households | 2023 |
| 2468 Property Limited | Professional & scientific | 2022 |
| 25 Gainsborough Limited | Real estate | 2024 |
| 26 Bradley Street Management Company Ltd | Extraterritorial | 2020 |
| 29 Victoria Road Management Company Limited | Households | 2019 |
| 3 Burnbury Road (Freehold) Limited | Real estate | 2011 |
| 3 Lancaster Buildings Ltd | Professional & scientific | 2015 |
| 3 Ravens Developments Ltd | Real estate | 2025 |
| 327 Investments Ltd | Real estate | 2012 |
| 33 Grove Terrace Management Company Limited | Households | 2003 |
| 38-44 Dochdwy Road Management Co. Ltd | Real estate | 2006 |
| 3D Property Investments Limited | Real estate | 1988 |
| 49 Plymouth Road Management Company Limited | Households | 1983 |
| 57 North Road Ltd. | Real estate | 2013 |
| 63 Westbourne Road Management Company | Households | 2020 |
| 64 Supplements Ltd | Wholesale & retail | 2023 |
| 66 Victoria Road (Penarth) Ltd | Real estate | 2014 |
| 7 Victoria Avenue Penarth Management Company Limited | Administrative & support | 2007 |
| 7BEANS Limited | Hospitality | 2024 |
| 7ROBOTS Limited | Arts & recreation | 2017 |
| 8 John ST Freehold Ltd | Households | 2024 |
| 88 Plymouth Road Management Company Limited | Households | 1997 |
| 9 Albert Crescent Limited | Households | 2023 |
| 9 Clive Crescent Management Company Limited | Households | 2020 |
| 9 Knights Walk RTM Company Limited | Real estate | 2009 |
| A & DK Properties Limited | Real estate | 2019 |
| A & LH Environmental Services Limited | Wholesale & retail | 2013 |
| A B Curtis Properties Ltd | Real estate | 2023 |
| A Critical Friend Limited | Professional & scientific | 2013 |
| A D C L Humphries & Sons Stonemasons Limited | Administrative & support | 2017 |
| A Finer Finish Ltd | Construction | 2025 |
| A G Herriott Site Services Limited | Construction | 1994 |
| A&J GIN Bars Ltd | Hospitality | 2018 |
| A&K Cleaning Services Ltd | Administrative & support | 2022 |
| A.G Dhaliwal's Ltd | Wholesale & retail | 2019 |
| A.L.H. Heritage Joinery Ltd | Manufacturing | 2024 |
| A.S. Renewable Energy Advisory Ltd | Professional & scientific | 2021 |
| AA Ionescu Ltd | Health & social care | 2017 |
| AA Media Print Management Limited | Professional & scientific | 2011 |
| Aaiza Ltd | Hospitality | 2021 |
| AAS Capital Ltd | Real estate | 2025 |
| ABI Hanah Ltd | Professional & scientific | 2022 |
| Abis Property Limited | Real estate | 2017 |
| Absolute Property Management Solutions Ltd | Real estate | 2012 |
| Academy 64 Limited | Education | 2021 |
| Access 2 Supplements UK Limited | Wholesale & retail | 2020 |
| Ace Glazing and Bifold Ltd | Construction | 2021 |
| Acer Ecology Ltd | Professional & scientific | 2011 |
| ACJ Property Limited | Real estate | 2003 |
| Acorn Aesthetics Ltd | Wholesale & retail | 2025 |
| Acorn Chiropractic (Penarth) Limited | Health & social care | 2023 |
| Acorn Diagnostics Ltd | Health & social care | 2021 |
| Acorn Dwellings Limited | Real estate | 2025 |
| Acorn Healthcare Services Ltd | Health & social care | 2021 |
| Active Learning Team Ltd | Education | 2016 |
| Active Logic Limited | Information & communication | 1985 |
| Aderyn Y BWN Limited | Extraterritorial | 2010 |
| Adkar Limited | Health & social care | 2014 |
| Adra Shop Ltd | Wholesale & retail | 2025 |
| Adventure Paws Ltd | Professional & scientific | 2020 |
| AE Holdings Ltd | Other services | 2020 |
| Aerovale Travel Ltd | Administrative & support | 2026 |
| Aesthetics 64 Ltd | Other services | 2021 |
| Affinity Complex Care Limited | Health & social care | 2025 |
| Afterglobe Ltd. | Wholesale & retail | 2016 |
| AG Herriott Holdings Limited | Financial services | 2021 |
| Agor Property Ltd | Real estate | 2025 |
| Agora Hospitality Ltd | Professional & scientific | 2023 |
| Aguilera Holdings Ltd | Financial services | 2023 |
| Ahmed Caravans Limited | Real estate | 2023 |
| AIM Higher Innovations Ltd | Information & communication | 2022 |
| Air Conditioning Cardiff Ltd | Construction | 2026 |
| Air Distribution Group Ltd | Wholesale & retail | 2016 |
| AK1 Barbers Ltd | Other services | 2024 |
| Albert Court Residents Management Company Limited | Hospitality | 1999 |
| Albi Homes Ltd | Construction | 2022 |
| Alekssiena Limited | Real estate | 2024 |
| Alembic Limited | Manufacturing | 1989 |
| Alembic Manufacturing Limited | Manufacturing | 2003 |