| AW Ammanford Ltd | Hospitality | 2025 |
| Awel Y Gwrhyd C.I.C. | Energy | 2011 |
| AWG Properties Ltd | Real estate | 2021 |
| AXI Engineering Limited | Manufacturing | 2018 |
| Ayzal Ltd | Hospitality | 2025 |
| B & R Factors Ltd | Wholesale & retail | 2009 |
| B Firm Pest Control Ltd | Administrative & support | 2015 |
| Bajirao UK Ltd | Wholesale & retail | 2023 |
| Bala Adido Ltd | Health & social care | 2025 |
| Barleybind Limited | Health & social care | 1991 |
| Barnard Rail Limited | Professional & scientific | 2017 |
| Bartypower Ltd | Energy | 2023 |
| Base Logistics Ltd | Transport & logistics | 2005 |
| BE Your Happy Place Ltd | Wholesale & retail | 2020 |
| Becs Developments Ltd | Real estate | 2025 |
| Beech Tree Rise Management Limited | Real estate | 2006 |
| Begold Tanning Limited | Other services | 2024 |
| Bethesda Clinical and Consultancy Services Ltd | Health & social care | 2023 |
| BGL Interiors Ltd | Construction | 2022 |
| Bickford Construction Limited | Construction | 2002 |
| Bickford Properties Limited | Real estate | 2017 |
| Biomass 4 Wales Limited | Extraterritorial | 2013 |
| Biosol Group Limited | Real estate | 2016 |
| Biosol Renewables UK Ltd | Construction | 2014 |
| Bistro on the Bay Ltd | Hospitality | 2023 |
| BK Installations Limited | Construction | 2017 |
| Bkind Mobile Holistic Therapies Ltd | Health & social care | 2021 |
| Black Mountain Building Services Ltd | Construction | 2017 |
| Black Mountain Dog Company Limited | Other services | 2025 |
| Black Mountain Tarmacadam Driveways Limited | Construction | 2021 |
| Blod Ltd | Real estate | 2020 |
| BNCARPENTRY23 Ltd | Manufacturing | 2025 |
| Bodytek Spraying Ltd | Wholesale & retail | 2026 |
| Boost Medical Doctors Limited | Health & social care | 2022 |
| Bootec Ltd | Manufacturing | 2003 |
| Bossa Investments Ltd | Financial services | 2020 |
| Boundary Stone Habitats Improvements Ltd | Education | 2011 |
| Bovi Cafe Limited | Hospitality | 2026 |
| BP Civil Engineering Services Ltd | Professional & scientific | 2023 |
| Bravura Cosmeceuticals Limited | Wholesale & retail | 2011 |
| Bribaudon Property Ltd | Real estate | 2020 |
| Broadleaf Flooring Ltd | Extraterritorial | 2020 |
| Broadleaf Timber Limited | Manufacturing | 2010 |
| Broody Marketplace Ltd | Wholesale & retail | 2026 |
| Bryan Moses Productions Limited | Information & communication | 2014 |
| Brynamman Cinema CYF | Arts & recreation | 2010 |
| Brynamman Napoli Pizza Limited | Hospitality | 2020 |
| Brynmwyn Residents Management Company Limited | Households | 2005 |
| Budoodles Gift Emporium Ltd | Wholesale & retail | 2018 |
| Bugail Consulting Ltd | Information & communication | 2013 |
| Business Suite Management Ltd | Administrative & support | 2026 |
| BY Figure 8 Limited | Other services | 2022 |
| C & D Heating and Renewables Limited | Construction | 2023 |
| C H Motor Company Limited | Wholesale & retail | 2008 |
| C M Construction Building & Tiling Ltd | Construction | 2022 |
| C S Jones Developments Limited | Construction | 2025 |
| C.R. Clarke & Co. (UK) Limited | Manufacturing | 1986 |
| Cable Technology Network Ltd | Manufacturing | 2020 |
| CAE Greynor Management Limited | Real estate | 2012 |
| Caedu Limited | Health & social care | 2022 |
| Caketisserie Limited | Hospitality | 2019 |
| Calan Films Ltd. | Information & communication | 2014 |
| Calon Breathwork Ltd | Health & social care | 2023 |
| Calow Evans Limited | Real estate | 2021 |
| Cambrian Asset Finance Limited | Financial services | 2008 |
| Canolfan Maerdy | Transport & logistics | 2008 |
| Canolfan Y Mynydd DU the Black Mountain Centre | Administrative & support | 2001 |
| Capitalise Your Finance Limited | Financial services | 2017 |
| Cardiff City Breaks Limited | Hospitality | 2017 |
| Care - Companions and Training Ltd | Administrative & support | 2026 |
| Cariad Confectionery Ltd | Wholesale & retail | 2022 |
| Carmarthen Consultancy Limited | Professional & scientific | 2014 |
| Carmarthenshire Construction Training Association Limited | Other services | 2008 |
| Carmarthenshire Property Solutions Ltd | Construction | 2019 |
| Carmarthenshire Tourism Association | Other services | 1998 |
| Cart 2 Door Ltd | Water & waste | 2025 |
| Carters Removals International Limited | Transport & logistics | 2025 |
| Cartreco Limited | Construction | 2022 |
| Cartref Tirydail Ltd | Real estate | 2014 |
| Cartrefi Dafydd Cyfyngedig | Real estate | 2024 |
| Castle Asset Holdings Limited | Professional & scientific | 2008 |
| Castle Garden Developments Limited | Construction | 2015 |
| Castle Reach Management Company Limited | Professional & scientific | 2004 |
| Castle Scaffolding (Wales) Ltd | Construction | 2007 |
| Catchcymru Ltd | Hospitality | 2024 |
| Catre Ltd. | Health & social care | 2021 |
| Catref Limited | Health & social care | 2021 |
| CCW Law Solicitors Limited | Administrative & support | 2006 |
| CDN Homes Ltd | Households | 2025 |
| CDN Planning (Wales) Ltd | Professional & scientific | 2005 |
| Cells Properties Limited | Real estate | 2026 |
| Celtic Craft Carpentry Limited | Manufacturing | 2025 |
| Celtic Green Energie Ltd | Construction | 2025 |
| Celtic Iron Limited | Manufacturing | 2019 |
| Celtic Quality Management (CQM) Ltd | Professional & scientific | 2020 |
| Cennen Properties Ltd | Real estate | 2022 |
| Cennen Solutions Ltd | Professional & scientific | 2017 |
| Cennen Wealth Asset Management Ltd | Financial services | 2023 |
| Centaur Real Estate Ltd | Real estate | 2026 |
| CFW Brickwork Limited | Manufacturing | 2025 |