| Capital Properties Limited | Real estate | 2005 |
| Capital Prosthetics Laboratory Limited | Health & social care | 2002 |
| Captivation House Ltd | Professional & scientific | 2015 |
| Cardiff and Vale Construction Limited | Water & waste | 2006 |
| Cardiff Autos Ltd | Wholesale & retail | 2022 |
| Cardiff Bay Boat Sales Limited | Administrative & support | 1994 |
| Cardiff Digital Print Limited | Manufacturing | 2013 |
| Cardiff Economic Research Associates Limited | Professional & scientific | 2020 |
| Cardiff Financial Partnership LLP | | 2001 |
| Cardiff Pain and Wellness Clinic Ltd | Health & social care | 2023 |
| Cardiff Shutters and Blinds Limited | Other services | 2021 |
| Cardiff Stone Masonry Ltd | Manufacturing | 2015 |
| Cardiff Wales Lesbian GAY Bisexual Transgender Mardi Gras | Arts & recreation | 2010 |
| Cardiff Window Cleaner Ltd | Administrative & support | 2014 |
| Cardo Energy Efficiency Limited | Professional & scientific | 2022 |
| Cardo Energy Limited | Construction | 2022 |
| Cardo Energy Solutions Limited | Construction | 2022 |
| Cards for Good Ltd | Wholesale & retail | 2024 |
| Careaw Ltd | Health & social care | 2025 |
| Caresorter Limited | Information & communication | 2021 |
| Carlux Limited | Wholesale & retail | 2023 |
| Carlux Service & MOT Centre Ltd | Wholesale & retail | 2026 |
| Carol Joy London Limited | Wholesale & retail | 2014 |
| Cartcore Ltd | Wholesale & retail | 2026 |
| Casa Martinez Investments Limited | Real estate | 2017 |
| Cascade Cleaning & Maintenance Ltd | Administrative & support | 2024 |
| Cassemis Property Limited | Real estate | 2025 |
| Cassia Limited | Professional & scientific | 2026 |
| Castleton Consultants Limited | Construction | 1993 |
| Cciba Ltd | Wholesale & retail | 2021 |
| Cdfi Group Ltd | Financial services | 2025 |
| CDP Health Outcomes Ltd | Health & social care | 2013 |
| Cebm Ltd | Professional & scientific | 2014 |
| Cecchi Professional Sales Consultants Limited | Professional & scientific | 2025 |
| Cedar Tree Project Developments Ltd | Construction | 2021 |
| CEL Transport Ltd | Transport & logistics | 2015 |
| Celtic Plumbing and Heating Ltd | Construction | 2002 |
| Celtic Urban Living Ltd | Construction | 2019 |
| Cenik Chemicals Limited | Wholesale & retail | 2021 |
| Central Construction Limited | Real estate | 2021 |
| Centralize Ltd | Information & communication | 2025 |
| Centre for Occupational and Health Psychology (Cohp) Penarth Ltd | Professional & scientific | 2025 |
| Cerispa Ltd | Manufacturing | 2016 |
| Cerus Fashion Limited | Wholesale & retail | 2017 |
| Ceva Property Limited | Real estate | 2021 |
| CG Energy Holdings Ltd | Real estate | 2022 |
| CG81 Investments Limited | Real estate | 2016 |
| CH Richards Properties Limited | Real estate | 2021 |
| Chad Patel Ltd | Professional & scientific | 2014 |
| Chalk Financial Planning Ltd | Financial services | 2026 |
| Chalkhouse Kitchens Ltd | Manufacturing | 2012 |
| Challenge Wales | Education | 2005 |
| Challenge Wales (Sales) Limited | Wholesale & retail | 2012 |
| Changing Hands Property Ltd | Construction | 2023 |
| Channel Electrical Systems Limited | Construction | 2017 |
| Channel View Court Residents Association Limited | Real estate | 1998 |
| Chanya TUM Home Limited | Arts & recreation | 2025 |
| Chapman & Co (Penarth) Limited | Professional & scientific | 2016 |
| Charged RV Ltd | Administrative & support | 2022 |
| Charlotte Rentals Limited | Extraterritorial | 2024 |
| Chaseblue Loans Ltd. | Financial services | 2007 |
| Chatchaya Spa Limited | Other services | 2024 |
| Chauffeur Connect Limited | Transport & logistics | 2016 |
| Chef GS Seafood and Grill Limited | Hospitality | 2025 |
| Cheryl Collectibles Limited | Wholesale & retail | 2025 |
| Child Health Care CYF | Health & social care | 2020 |
| Chilli Bean Consulting Limited | Administrative & support | 2020 |
| Chloe & Co (Penarth ) Limited | Other services | 2016 |
| Chris Evans Business Consultancy Ltd | Professional & scientific | 2015 |
| Circular Resource Specialists Ltd | Professional & scientific | 2022 |
| Cissbury View Holdings Ltd | Financial services | 2024 |
| City Base Accommodation Ltd | Real estate | 2025 |
| City Wharf Freehold Company Ltd | Households | 2026 |
| City Wharf RTM Company Limited | Real estate | 2010 |
| CJ International Beauty Limited | Other services | 2004 |
| CJ Solutions Ltd | Professional & scientific | 2024 |
| Cladconsulting Limited | Professional & scientific | 2026 |
| Claramae Edwards Limited | Health & social care | 2024 |
| Clarequity Ltd | Professional & scientific | 2026 |
| Clarke & Scrivens Estates Limited | Professional & scientific | 2016 |
| Clean GEN Solutions Ltd | Construction | 2024 |
| Clean Lean Kitchen Ltd | Manufacturing | 2018 |
| Cleaned Footprint Ltd | Construction | 2012 |
| Clear Solutions Management Ltd | Administrative & support | 2019 |
| CLH Property Limited | Real estate | 2024 |
| Clifden Mortgage Advisers Limited | Financial services | 2020 |
| Cliffside Shipping Co. Ltd | Transport & logistics | 2018 |
| CLM Amazon Limited | Transport & logistics | 2025 |
| Cloud River Limited | Professional & scientific | 2014 |
| CMJ Social Care Ltd | Health & social care | 2022 |
| Cmjv Ltd | Professional & scientific | 2026 |
| Cmka Holdings Ltd | Professional & scientific | 2019 |
| Cmrd Projects Limited | Information & communication | 2015 |
| CMS Train Ltd | Education | 2024 |
| CMS Training Solutions Ltd | Education | 2012 |
| Cnectwales Ltd | Other services | 2023 |
| Cnem Group Limited | Health & social care | 2016 |
| Coach Buddy Ltd | Information & communication | 2026 |
| Coaching Nutrition Limited | Health & social care | 2021 |
| Coast Investment Properties Ltd. | Real estate | 2016 |