| CC Traders Ltd | Wholesale & retail | 2025 |
| Cctv Services Limited | Administrative & support | 2003 |
| Cedar Court B1 RTM Company Limited | Households | 2019 |
| Cedar Court B2 RTM Company Limited | Households | 2019 |
| Ceginau Aspire Kitchens Cyfyngedig | Wholesale & retail | 2020 |
| Celtic Bars Ltd | Hospitality | 2025 |
| Celtic Electrical & Energy Ltd | Construction | 2026 |
| Celtic Vibes Limited | Hospitality | 2026 |
| Central House Garage Ltd | Wholesale & retail | 2013 |
| Centrebound Limited | Administrative & support | 2013 |
| Certain Knowledge Limited | Financial services | 2006 |
| CFP Worldwide Limited | Professional & scientific | 2022 |
| CGI International Trade Ltd | Real estate | 2025 |
| Cgi-Web.Co.Uk Ltd | Information & communication | 2011 |
| Chandler Reynolds Limited | Wholesale & retail | 2002 |
| Change & Transformation in Action Limited | Professional & scientific | 2015 |
| Channel People Limited | Administrative & support | 2016 |
| Charles Cordell Limited | Wholesale & retail | 2022 |
| Chasebell Ltd | Health & social care | 1999 |
| Chatsworth Hotel (Llandudno) Limited | Hospitality | 1992 |
| Chatsworth Hotel Limited | Hospitality | 2000 |
| Chicane Automotive Management Ltd | Financial services | 2018 |
| Chocolate Box (Craig Y DON) Ltd | Wholesale & retail | 2013 |
| Chris Marshall International Ltd | Information & communication | 2022 |
| Church Walks 2015 Limited | Real estate | 2015 |
| Cimatti Renewables Ltd | Manufacturing | 2026 |
| Cimattis Plastering Ltd | Construction | 2025 |
| Cintra Holiday Lets Ltd | Real estate | 2024 |
| CJD Renewables Ltd | Professional & scientific | 2026 |
| Clavid Limited | Hospitality | 2022 |
| Cleaning for Mental Health Limited | Administrative & support | 2023 |
| Click Systems Group Ltd | Information & communication | 2026 |
| Clifton Apartments (Llandudno) Ltd. | Hospitality | 2004 |
| Clifton Road (Llandudno) Management Company Limited | Households | 2019 |
| Clinton James Limited | Other services | 2002 |
| CLO and Co Hair Studio Limited | Other services | 2023 |
| Clothes for Work Limited | Wholesale & retail | 2002 |
| Cloud Accounting North Wales Limited | Professional & scientific | 2018 |
| Cloud Laundry Ltd | Administrative & support | 2024 |
| Clover Home Improvments Ltd | Wholesale & retail | 2021 |
| CMG Build Works Ltd | Construction | 2018 |
| Co & Associates Limited | Administrative & support | 2017 |
| Coabaste Properties Limited | Real estate | 1963 |
| Coached by CLO Ltd | Arts & recreation | 2025 |
| Coast & Marina Properties Ltd | Real estate | 2010 |
| Coastline Property Portfolio Ltd | Real estate | 2022 |
| Coco & Lucian Ltd | Hospitality | 2022 |
| Code Consulting Limited | Information & communication | 2017 |
| Coed 2011 Limited | Health & social care | 2011 |
| Coed Isaf Nursing Home Limited | Health & social care | 2003 |
| Coffee Roasters Ltd | Manufacturing | 2005 |
| Cole Renewables Limited | Manufacturing | 2024 |
| Colin Williams Painter & Decorator Limited | Construction | 2005 |
| Combined Tyres & Autocare Limited | Extraterritorial | 2009 |
| Compact Crane Hire Ltd | Administrative & support | 2024 |
| Condor Hotels Limited | Hospitality | 2016 |
| Conner's Place Ltd. | Health & social care | 2019 |
| Contract Solar Ltd | Construction | 2022 |
| Convert and Profit Ltd | Information & communication | 2019 |
| Conway Road Limited | Professional & scientific | 2015 |
| Conwy Consulting Ltd | Extraterritorial | 2007 |
| Conwy Heating Solutions Ltd | Construction | 2025 |
| Conwy Holdings and Investments Ltd | Real estate | 2023 |
| Conwy Holiday Cottages Limited | Real estate | 2018 |
| Conwy Holiday Homes Limited | Administrative & support | 2021 |
| Conwy Motor-Cycle Club Limited | Arts & recreation | 2003 |
| Conwy Plastics Moulding Limited | Manufacturing | 2026 |
| Conwy Property Maintenance Limited | Other services | 2015 |
| Conwy Valley Solar Limited | Construction | 2024 |
| Conwy Valley Windows and Conservatories Ltd. | Wholesale & retail | 2009 |
| Conwy Valley Windows Ltd | Extraterritorial | 2012 |
| Copamor Limited | Real estate | 2022 |
| Cornerstones Resourcing Limited | Administrative & support | 2013 |
| Court Street Garages (Llandudno) Ltd | Wholesale & retail | 2005 |
| Cowiehorsie Limited | Health & social care | 2015 |
| Craft Beer Cave Ltd | Wholesale & retail | 2026 |
| Craig Y DON Dental Limited | Health & social care | 2015 |
| Craig-Y-Don Management Co. Limited | Households | 1983 |
| Cressington Management Limited | Real estate | 2006 |
| Crib Goch Outdoor World Limited | Wholesale & retail | 2009 |
| Cricket Ground Equipment Limited | Arts & recreation | 2007 |
| Croeso Ltd | Professional & scientific | 2016 |
| Crows Nest Management Company Limited | Professional & scientific | 2008 |
| Crows Nest Retreats Ltd | Real estate | 2023 |
| Crtv Drip Marketing Ltd | Professional & scientific | 2026 |
| Cruglwyn CYF | Energy | 2014 |
| CST Consultancy Ltd | Professional & scientific | 2013 |
| CTC Hair and Beauty Supplies Limited | Wholesale & retail | 2006 |
| Cyngor AR Bopeth Cylch Conwy District Citizens Advice Bureau | Information & communication | 2006 |
| Cysgod Y Capel Management Company Limited | Households | 2015 |
| D & a Energy Consultants Limited | Professional & scientific | 2014 |
| D & G Property Developments Limited | Real estate | 2007 |
| D & L Developments (Llandudno) Ltd | Construction | 2003 |
| D a Southern Consulting Ltd | Professional & scientific | 2015 |
| D Cousins Decorators Ltd | Construction | 2019 |
| D R Property (1928) Ltd | Real estate | 1928 |
| D Seager Ltd | Construction | 2020 |
| D&G Building Contractors Limited | Construction | 2001 |
| D&I BRO RO Ltd | Other services | 2024 |
| D.Talbot Limited | Construction | 2025 |