| Buby Ltd | Transport & logistics | 2023 |
| Buchwunder Ltd | Arts & recreation | 2024 |
| Builders Hardware Direct Ltd | Wholesale & retail | 2021 |
| Burger Bros Llanelli Ltd | Hospitality | 2023 |
| Burns Building & Plastering Ltd | Construction | 2015 |
| Business and Vehicle Finance Ltd. | Wholesale & retail | 2001 |
| Business Cost Review Limited | Administrative & support | 2011 |
| Business Finance Direct Ltd | Professional & scientific | 2022 |
| Business Growth Mentors Ltd | Professional & scientific | 2006 |
| Butterfly HQ CIC | Professional & scientific | 2023 |
| Bwlchyfedwen Limited | Agriculture & fishing | 2003 |
| Bwydydd Conwy Ltd | Wholesale & retail | 2014 |
| Bygone Cars Limited | Administrative & support | 2003 |
| Bzams Ltd | Wholesale & retail | 2017 |
| C & S Williams Properties Ltd | Administrative & support | 2018 |
| C and G Hospitality Limited | Hospitality | 2020 |
| C EMB Print Limited | Other services | 2019 |
| C H Llwyd Limited | Professional & scientific | 2007 |
| C K'S Supermarket Limited | Wholesale & retail | 1998 |
| C Payne Plastering Ltd | Construction | 2025 |
| C Silcox Family Funeral Directors Ltd | Other services | 2025 |
| C&C Steel Structures Ltd | Construction | 2023 |
| C&M Motors (Llanelli) Ltd | Wholesale & retail | 2025 |
| C-View Pest Control Services Ltd | Administrative & support | 2017 |
| C.C Gardening Fencing Services Limited | Administrative & support | 2024 |
| C.S.A. Construction Limited | Administrative & support | 1994 |
| C2K - Concept to Key Limited | Construction | 2020 |
| Cadarn Services Ltd | Professional & scientific | 2020 |
| CAE Canfas Farm Limited | Agriculture & fishing | 2026 |
| CAE Felin Ltd | Construction | 2003 |
| Cae'R Ffair Ltd | Education | 2010 |
| Caffi Cynnes Cyfyngedig | Hospitality | 2004 |
| Caffi Pafiliwn Ltd | Hospitality | 2025 |
| Caffi Y Tebot Limited | Hospitality | 2026 |
| Caitlyn Properties Ltd | Real estate | 2024 |
| Call a CAB (Carmarthenshire) Ltd | Transport & logistics | 2013 |
| Calon Custom Clothing Ltd | Manufacturing | 2022 |
| Calon Homecare Carmarthenshire Limited | Other services | 2023 |
| Calon Mortgages Ltd | Financial services | 2023 |
| Calqo Limited | Information & communication | 2025 |
| Calred Ltd | Real estate | 2025 |
| Cambrian Sports Bar Ltd | Hospitality | 2022 |
| Cambrian Technical Solutions Limited | Manufacturing | 2014 |
| Cambrian Ventures Limited | Professional & scientific | 2018 |
| Candy's Properties Limited | Real estate | 2022 |
| Cannings Investments Ltd | Real estate | 2025 |
| Canolfan Tabor CYF | Professional & scientific | 2008 |
| Car Gateway Ltd | Wholesale & retail | 2026 |
| Car Valets Pontyates Ltd | Other services | 2021 |
| Carbon Crusaders Limited | Manufacturing | 2024 |
| Cardiff & South Wales Yacht Services Limited | Manufacturing | 2018 |
| Carers Trust Crossroads West Wales Ltd | Health & social care | 2007 |
| Cariad Spiritual Ltd | Manufacturing | 2025 |
| Carlo's Italian Fish Bar Limited | Hospitality | 2021 |
| Carmarthenshire Citizens Advice Bureau | Administrative & support | 2011 |
| Carmarthenshire Ltd | Construction | 2025 |
| Carmarthenshire School of Gymnastics Limited | Arts & recreation | 2011 |
| Carmarthenshire Wizards Ltd | Arts & recreation | 2024 |
| Carmichaels Building Services Limited | Construction | 1990 |
| Carmody Network Services Ltd | Information & communication | 2021 |
| Carnwyllion Ltd | Real estate | 2024 |
| Carnwyllon Wealth Management Limited | Financial services | 2009 |
| Carp King Competitions Ltd | Arts & recreation | 2026 |
| Carreg Properties Limited | Construction | 2021 |
| Carrington Atlantic Ltd | Financial services | 2025 |
| Cartref CGT Limited | Real estate | 2025 |
| Cartref Estate Agents Ltd | Real estate | 2020 |
| Cartref Financial Services Limited | Financial services | 2014 |
| Cartref Oddi Cartref Limited | Hospitality | 2024 |
| Cartrefi CWM Gwendraeth CYF. | Construction | 2025 |
| Cartrefi DRW Ltd | Real estate | 2024 |
| Cartrefi Thomas Ltd | Real estate | 2023 |
| Caru Canu CYF | Education | 2024 |
| Carwyn Walters Haulage Ltd | Administrative & support | 2017 |
| Casa Cleaning Limited | Administrative & support | 2024 |
| Castell Howell Foods Limited | Wholesale & retail | 1988 |
| Castle Rock Estates Ltd | Real estate | 2025 |
| Cathedral Care Limited | Health & social care | 1991 |
| Catherine Tregenna Ltd | Arts & recreation | 2007 |
| Catref Clyd Properties Ltd | Real estate | 2023 |
| Catrin Beard CYF | Professional & scientific | 2014 |
| Caushaj Limited | Households | 2024 |
| Cavendish Castle Limited | Construction | 2008 |
| CC HR Consulting Ltd | Administrative & support | 2019 |
| CC Repairs Limited | Wholesale & retail | 2019 |
| Ccta Enterprises Limited | Education | 1993 |
| CCW Electrical Limited | Manufacturing | 2015 |
| CDM Data Systems Limited | Information & communication | 2003 |
| Cdmn Sheehan Ltd | Real estate | 2018 |
| Cedartree Construction Limited | Construction | 2020 |
| Cefneithin RFC Limited | Arts & recreation | 2017 |
| Celebrity Mattress Limited | Administrative & support | 2017 |
| Cellular Agriculture Holdings Limited | Financial services | 2025 |
| Cellular Agriculture IP Limited | Financial services | 2025 |
| Cellular Agriculture Ltd | Manufacturing | 2016 |
| Cellular Agriculture Parent Limited | Financial services | 2025 |
| Celsius Installations & Services Limited | Construction | 2014 |
| Celt Homes Limited | Construction | 2019 |
| Celtic Broadband Solutions Ltd | Information & communication | 2023 |
| Celtic Cladding Services Ltd | Manufacturing | 2009 |