| Cardiff Arms Environmental Services Limited | Construction | 2005 |
| Cardiff Arms Park Redevelopment Limited | Construction | 2021 |
| Cardiff Arms Plant Hire Ltd | Administrative & support | 2019 |
| Cardiff Arms Waste Management Limited | Water & waste | 2013 |
| Cardiff Asphalt Limited | Construction | 2022 |
| Cardiff Athletics | Other services | 2018 |
| Cardiff Auto Revival Limited | Wholesale & retail | 1988 |
| Cardiff Autonomous Social Centre CIC | Hospitality | 2026 |
| Cardiff Autoscreens Limited | Wholesale & retail | 2003 |
| Cardiff Bakery Ltd | Manufacturing | 2025 |
| Cardiff Balaia (1990) Limited | Hospitality | 1990 |
| Cardiff Balloons Limited | Wholesale & retail | 2024 |
| Cardiff Bar Co Ltd | Hospitality | 2024 |
| Cardiff Barbershop Limited | Other services | 2017 |
| Cardiff Bathroom Store Ltd | Wholesale & retail | 2022 |
| Cardiff Bay Auto Centre Limited | Wholesale & retail | 2000 |
| Cardiff Bay Care Ltd | Health & social care | 2025 |
| Cardiff Bay Cruises Limited | Transport & logistics | 2001 |
| Cardiff Bay Estates Construction Limited | Construction | 2017 |
| Cardiff Bay Estates Limited | Real estate | 2016 |
| Cardiff Bay Kayaking Limited | Arts & recreation | 2022 |
| Cardiff Bay Nails and Beauty Ltd | Other services | 2025 |
| Cardiff Bay Personal Fitness Ltd | Arts & recreation | 2012 |
| Cardiff Bay Print Ltd | Manufacturing | 2023 |
| Cardiff Bay Printing Ltd | Manufacturing | 2015 |
| Cardiff Bay Truck Services Limited | Wholesale & retail | 1997 |
| Cardiff Baylink Limited | Transport & logistics | 2002 |
| Cardiff Beach Volleyball Club Ltd | Arts & recreation | 2017 |
| Cardiff Beauty Clinic Limited | Other services | 2016 |
| Cardiff Bi-Folding Doors Ltd | Construction | 2013 |
| Cardiff BID Ltd | Administrative & support | 2016 |
| Cardiff Blinds Limited | Manufacturing | 2016 |
| Cardiff Boat Sales Limited | Wholesale & retail | 2021 |
| Cardiff Boat Tour Limited | Transport & logistics | 2011 |
| Cardiff Bookkeeping and Accountancy Services Ltd | Professional & scientific | 2017 |
| Cardiff Bridal Limited | Wholesale & retail | 1993 |
| Cardiff Building and Maintenance Ltd | Construction | 2025 |
| Cardiff Business Club Limited | Other services | 1956 |
| Cardiff Business Park (1994) Limited | Professional & scientific | 1994 |
| Cardiff Business Technology Centre Limited | Administrative & support | 1986 |
| Cardiff Cabs/Taxi UK Limited | Professional & scientific | 2018 |
| Cardiff Cafe Limited | Hospitality | 2021 |
| Cardiff Campers Ltd | Administrative & support | 2026 |
| Cardiff Car & Van Sales Ltd | Wholesale & retail | 2024 |
| Cardiff Car Care Limited | Wholesale & retail | 2010 |
| Cardiff Car Cosmetics Ltd | Wholesale & retail | 2025 |
| Cardiff Car Sales Ltd | Wholesale & retail | 2024 |
| Cardiff Caravan & Camping Accessories Ltd | Wholesale & retail | 2020 |
| Cardiff Care Limited | Health & social care | 2023 |
| Cardiff Carers Ltd | Administrative & support | 2018 |
| Cardiff Cargo Bikes Ltd | Wholesale & retail | 2024 |
| Cardiff Cars Action Vehicles Ltd | Administrative & support | 2026 |
| Cardiff Cars Ltd | Wholesale & retail | 2025 |
| Cardiff Cars Recovery and Transportation Ltd | Wholesale & retail | 2021 |
| Cardiff Centre for Astrobiology Limited | Professional & scientific | 2011 |
| Cardiff Cheesemongers Ltd | Wholesale & retail | 2025 |
| Cardiff Chicken Ltd | Hospitality | 2023 |
| Cardiff Chimney Stacks Limited | Other services | 2020 |
| Cardiff Chinese Restaurant Ltd | Hospitality | 2023 |
| Cardiff Chiropractic Care Limited | Health & social care | 2026 |
| Cardiff City (House of Sport) Limited | Arts & recreation | 2010 |
| Cardiff City Apartments Limited | Real estate | 2007 |
| Cardiff City Auctions Limited | Administrative & support | 2022 |
| Cardiff City Farm Limited | Agriculture & fishing | 2018 |
| Cardiff City FC Community Foundation | Education | 2009 |
| Cardiff City Football Club (Holdings) Limited | Arts & recreation | 2000 |
| Cardiff City Football Club Limited | Arts & recreation | 1910 |
| Cardiff City House Ltd | Hospitality | 2019 |
| Cardiff City Ladies Football Club Trustees Ltd | Other services | 2023 |
| Cardiff City Phones Ltd | Other services | 2024 |
| Cardiff City Premier Seating Limited | Arts & recreation | 2007 |
| Cardiff City Shawarma Ltd | Hospitality | 2025 |
| Cardiff City Skin Doctor Ltd | Other services | 2019 |
| Cardiff City Stadium Limited | Arts & recreation | 2005 |
| Cardiff City Transport Services Limited | Transport & logistics | 1986 |
| Cardiff Cleaners Ltd | Administrative & support | 2021 |
| Cardiff Cleaning Company Limited | Other services | 2016 |
| Cardiff Cleaning Group Ltd | Administrative & support | 2026 |
| Cardiff Cleaning Services Limited | Administrative & support | 2007 |
| Cardiff Cleaning Solutions Ltd | Administrative & support | 2024 |
| Cardiff Coffi Company Ltd | Hospitality | 2025 |
| Cardiff Cohousing Ltd | Real estate | 2020 |
| Cardiff College Enterprises Limited | Education | 1993 |
| Cardiff Colour Print Ltd | | 1986 |
| Cardiff Commissioning Limited | Construction | 1988 |
| Cardiff Community Meetup Limited | Arts & recreation | 2024 |
| Cardiff Community Sawna CIC | Other services | 2025 |
| Cardiff Community Times Ltd | Professional & scientific | 2009 |
| Cardiff Computer Centre Ltd | Information & communication | 2013 |
| Cardiff Concrete Polishing Limited | Administrative & support | 2021 |
| Cardiff Conservation Volunteers | Administrative & support | 1996 |
| Cardiff Controls Ltd | Manufacturing | 2024 |
| Cardiff Cooling Limited | Energy | 2024 |
| Cardiff Corporate Hospitality Ltd | Hospitality | 2017 |
| Cardiff Cosmetic Centre Limited | Real estate | 2014 |
| Cardiff Creative Ltd | Wholesale & retail | 2018 |
| Cardiff Cruises Ltd | Transport & logistics | 2007 |
| Cardiff Customs Limited | Wholesale & retail | 2023 |
| Cardiff Cycle Workshop Ltd | Education | 2007 |
| Cardiff Dance Festival | Arts & recreation | 2013 |