| Concoxia Ltd | Information & communication | 2018 |
| Concrete Grooving Limited | Construction | 2015 |
| Concrete Pumping Wales Ltd | Construction | 2018 |
| Conquer Fitness Coaching Ltd | Education | 2023 |
| Conquer Teamwear Limited | Wholesale & retail | 2021 |
| Container Cache Ltd | Real estate | 2025 |
| Continental Leisure Holdings Ltd | Professional & scientific | 2009 |
| Continental Leisure Properties Ltd | Real estate | 2009 |
| Continental Leisure Vehicles Limited | Wholesale & retail | 1988 |
| Continental Retail Ltd | Wholesale & retail | 2019 |
| Convor Ltd | Construction | 2025 |
| Cool Home Systems Limited | Construction | 2023 |
| Copa Installations Ltd | Construction | 2022 |
| Coral Friend Limited | Real estate | 2009 |
| Cordoba Foods Ltd | Hospitality | 2020 |
| Corduroy Dog Properties Limited | Real estate | 2021 |
| Cornhwrdd Farm Limited | Agriculture & fishing | 2024 |
| Cortexia Ltd | Extraterritorial | 2009 |
| Coshprop Ltd | Construction | 2023 |
| Cosimetti Investments Limited | Real estate | 2025 |
| Cosmeditech Limited | Manufacturing | 2023 |
| Country Pubs (Wales) Ltd | Real estate | 2006 |
| County Cycles Limited | Wholesale & retail | 2006 |
| CPA Horticulture Limited | Administrative & support | 2002 |
| CPD Caerbryn & Saron AFC | Arts & recreation | 2025 |
| CPD Llangennech AFC Ltd | Arts & recreation | 2024 |
| CRA MMA Ltd | Arts & recreation | 2018 |
| Craig Edwards GAS and Heating Services Ltd | Construction | 2020 |
| Craig Ewers Academy Limited | Arts & recreation | 2023 |
| Crane AID Service Company Limited | Manufacturing | 2003 |
| Crankshaw Property Holdings Ltd | Real estate | 2021 |
| Crazie Catering Limited | Hospitality | 2019 |
| Creations by Sarah Ltd | Wholesale & retail | 2025 |
| Creativeehome Ltd | Construction | 2023 |
| Creo Construction Limited | Construction | 2011 |
| Creo Hydrogen Storage Systems Ltd | Manufacturing | 2019 |
| Creo International Ltd | Professional & scientific | 2020 |
| Creo Manufacturing Limited | Manufacturing | 2009 |
| Cressall Properties Ltd | Real estate | 2023 |
| Crest Coatings Ltd | Manufacturing | 2026 |
| Crisp & FRY Caterers Limited | Hospitality | 1976 |
| Crixus Deliveries Ltd | Transport & logistics | 2024 |
| CRK Investments Limited | Real estate | 2003 |
| Croeso Adref Ltd | Real estate | 2025 |
| Croeso Solutions Limited | Real estate | 2003 |
| Cross Hands Chiropractic Clinic Limited | Health & social care | 2005 |
| Cross Hands Commericals Limited | Wholesale & retail | 2009 |
| Cross Hands Motors Limited | Wholesale & retail | 2025 |
| Cross Handsuk Ltd | Hospitality | 2025 |
| Cross Valley Ltd | Hospitality | 2017 |
| Crosshands ATF & Tacho Centre Ltd | Wholesale & retail | 2023 |
| Crosshands Flooring Ltd | Administrative & support | 2025 |
| Crosshands Home Services Limited | Health & social care | 2014 |
| Crosshands Hydraulic Services LLP | | 2004 |
| Crosshands Laundry Limited | Other services | 2006 |
| Crosshands Training Ltd | Education | 2016 |
| CRS Construction and Maintenance Ltd | Construction | 2017 |
| Crush Supplements Ltd | Manufacturing | 2023 |
| Crystal Carpets & Flooring Ltd | Construction | 2017 |
| CSA Hygiene Ltd | Administrative & support | 2006 |
| CSA Site Services Limited | Administrative & support | 1998 |
| CSI Llanelli Limited | Construction | 2009 |
| CT Eco Ltd | Construction | 2020 |
| CT Logistics Ltd | Transport & logistics | 2026 |
| CTJ Electrical Ltd | Construction | 2024 |
| Cuda Broadcast Ltd | Information & communication | 2011 |
| Curry's Building Contractors Llanelli Ltd | Construction | 2024 |
| CUST6RD Ltd | Professional & scientific | 2018 |
| Custom Printz Ltd | Wholesale & retail | 2026 |
| CVD Asset Holdings Ltd | Financial services | 2025 |
| CWJ Properties Limited | Real estate | 2025 |
| CWM Construction Ltd | Construction | 2013 |
| CWM Glân Exterior Cleaning Ltd | Administrative & support | 2025 |
| Cwmgwili Enterprise Limited | Financial services | 2023 |
| Cwmpasu CYF. | Professional & scientific | 2016 |
| Cwsg Ltd | Health & social care | 2014 |
| Cwtch Cymraeg Ltd | Health & social care | 2025 |
| Cwtch TY Gwyn Limited | Hospitality | 2015 |
| Cwtsh Chocolate Ltd | Wholesale & retail | 2012 |
| CYB Trading Limited | Hospitality | 2024 |
| Cyca Wales Limited | Administrative & support | 2010 |
| Cycle Champs Ltd | Other services | 2021 |
| Cycling Tours (Wales) Limited | Administrative & support | 2025 |
| Cyfle Ltd | Professional & scientific | 2022 |
| Cyhoeddiadau Barn CYF | Information & communication | 1997 |
| Cymri Connect Ltd | Wholesale & retail | 2025 |
| Cymric Archers Limited | Arts & recreation | 2025 |
| Cymru Care Training Limited | Education | 1993 |
| Cysgod Y Llan Management Company Limited | Households | 2004 |
| D & P Jeffreys Developments Ltd | Real estate | 2016 |
| D & S Carpets (Wales) Limited | Wholesale & retail | 2003 |
| D James & K Morgan Property Limited | Real estate | 2024 |
| D R Taxis Llanelli Ltd | Transport & logistics | 2019 |
| D&G Rees Ltd | Hospitality | 2025 |
| D.A.E. Aerospace Limited | Manufacturing | 2015 |
| D.T.H. Walters & Sons Limited | Transport & logistics | 1988 |
| Dafen Service Station Limited | Water & waste | 1979 |
| Dafen Warehousing Solutions Limited | Transport & logistics | 2008 |
| Daioni Yoga Ltd | Other services | 2021 |
| Dale Retail Trading Ltd | Wholesale & retail | 2022 |