| Cathedral Green Management Company Limited | Households | 2003 |
| Cathedral House (Pontcanna) Ltd | Households | 2020 |
| Cathedral Interior Contractors Limited | Construction | 2006 |
| Cathedral Medical Limited | Health & social care | 2013 |
| Cathedral Orthodontics Limited | Health & social care | 2009 |
| Cathedral Road Management Ltd | Real estate | 2025 |
| Cathedral Road Properties LLP | | 2001 |
| Cathedral Road Service Station Ltd | Wholesale & retail | 2021 |
| Cathedral Sleep Clinic Ltd | Health & social care | 2024 |
| Cathedral View Properties Limited | Real estate | 2015 |
| Catherine Catering Ltd | Hospitality | 2017 |
| Catherine Pratt Ltd | Professional & scientific | 2026 |
| Cathod DU Consultancy Ltd | Professional & scientific | 2017 |
| Cathy Int'L Trading Limited | Administrative & support | 2021 |
| Catjk Trading Ltd | Wholesale & retail | 2025 |
| Catlin Sawer Taverns Ltd | Hospitality | 2016 |
| Catrefi YN Y Capital Ltd | Real estate | 2025 |
| Cats and Cream Ltd | Information & communication | 2016 |
| Cats Whiskers Hair Cardiff Limited | Other services | 2022 |
| Catsci Group Holdings Limited | Financial services | 2022 |
| Catsci Holdings Ltd | Professional & scientific | 2021 |
| Catsci Invest Ltd | Financial services | 2022 |
| Catsci Ltd | Professional & scientific | 2010 |
| Catta Solutions Ltd. | Wholesale & retail | 2016 |
| Cattolico Intelligence Ltd | Public administration | 2018 |
| Cattowesley Ltd | Health & social care | 2016 |
| Catyh Limited | Real estate | 2018 |
| Caukin Construct Ltd | Construction | 2026 |
| Caur Consult Limited | Professional & scientific | 2024 |
| Causeway Connect Ltd | Professional & scientific | 2018 |
| Caval SAS Ltd | Wholesale & retail | 2025 |
| Cavalieri IT Ltd | Information & communication | 2016 |
| Cavalieri Rentals Ltd | Real estate | 2018 |
| Cavalieri Serviced Rentals Ltd | Real estate | 2016 |
| Cavally Sons & Co Ltd | Information & communication | 2019 |
| Cavalry 1854 Ltd | Wholesale & retail | 2013 |
| Cavara House Ltd | Wholesale & retail | 2025 |
| Cavaras Services Ltd | Administrative & support | 2021 |
| Cavc Campus Holding Limited | Financial services | 2024 |
| Cavc Campus Limited | Construction | 2024 |
| Cave of Gold Ltd | Wholesale & retail | 2018 |
| Cavefish Ltd | Information & communication | 2023 |
| Cavendish Basements Limited | Construction | 2015 |
| Cavendish Care Limited | Health & social care | 2020 |
| Cavendish Consulting Cymru Limited | Professional & scientific | 2011 |
| Cavendish Country Pubs Limited | Hospitality | 2023 |
| Cavendish Finance Ltd | Financial services | 2013 |
| Cavendish Plumbers Limited | Construction | 2009 |
| Cavendown Ltd | Wholesale & retail | 2025 |
| Cavex Limited | Information & communication | 2011 |
| Cavionito Ltd | Information & communication | 2025 |
| Cawoods.Net Limited | Construction | 2005 |
| Cayan Foods Centre Limited | Wholesale & retail | 2018 |
| Cayman Installations Limited | Construction | 2019 |
| Cayo Ltd | Hospitality | 2007 |
| Caystard Group Intl. Ltd | Information & communication | 2025 |
| Cazam Property Ltd | Real estate | 2025 |
| Cazbah Limited | Professional & scientific | 2006 |
| Cazpian Hodings Ltd | Wholesale & retail | 2026 |
| CB Decorating Ltd | Administrative & support | 2019 |
| CB Investment Holding Ltd | Financial services | 2024 |
| CB Ningbo Technology Co., Ltd | Extraterritorial | 2020 |
| CB4 Theatre Ltd | Arts & recreation | 2019 |
| CB9 Limited | Information & communication | 2011 |
| CBC Broadcast Centre Limited | Information & communication | 2024 |
| CBD and Hemp Ltd | Wholesale & retail | 2018 |
| CBD Interiors Limited | Construction | 2009 |
| CBD Mobile Chef Ltd | Hospitality | 2023 |
| CBD Spring Water Ltd | Manufacturing | 2019 |
| Cbdean Ltd | Administrative & support | 2025 |
| Cbdvaperus Ltd | Health & social care | 2017 |
| Cberry WT Forex Limited | Financial services | 2023 |
| Cbf-Mech Ltd | Construction | 2017 |
| Cbfba Ltd | Hospitality | 2025 |
| CBG Consulting Limited | Information & communication | 2025 |
| CBH Accounting Solutions Ltd | Professional & scientific | 2020 |
| CBI Interiors Limited | Construction | 2017 |
| CBL Barbers Ltd | Other services | 2023 |
| CBL Solutions Ltd | Wholesale & retail | 2025 |
| CBM Property Solutions Ltd | Real estate | 2024 |
| Cbof Group Limited | Wholesale & retail | 2014 |
| Cbof Limited | Wholesale & retail | 2014 |
| CBR Developments Limited | Construction | 2015 |
| Cbrex Technologies UK Limited | Information & communication | 2020 |
| CBS Plumbing, Heating and Mechanical Limited | Construction | 2023 |
| CBT Artherapy Limited | Health & social care | 2014 |
| CC Cleaning Group Ltd | Administrative & support | 2019 |
| CC Distro Ltd | Wholesale & retail | 2018 |
| CC Plumbing and GAS Ltd | Construction | 2026 |
| Cc&M Plant and Maintenance Services Limited | Construction | 2009 |
| CC7R1 Ltd | Health & social care | 2016 |
| Ccct Services Ltd | Energy | 2019 |
| Ccdavies Limited | Real estate | 2015 |
| Ccfc Development Ltd | Arts & recreation | 2021 |
| CCH Holding Ltd | Financial services | 2025 |
| Cchalklettings Ltd | Real estate | 2020 |
| CCK Service Ltd | Other services | 2019 |
| Cckf (UK) Limited | Education | 2016 |
| CCL (Rent Collection) Limited | Real estate | 2019 |
| CCM Associates (Cardiff) Limited | Real estate | 2008 |