| Cardiff Deep Clean Specialists Ltd | Other services | 2010 |
| Cardiff Demolition Company Limited | Construction | 2000 |
| Cardiff Development Ltd | Real estate | 2021 |
| Cardiff Diesel Services Limited | Manufacturing | 1998 |
| Cardiff Distillery Ltd | Manufacturing | 2019 |
| Cardiff Draconians FC Limited | Arts & recreation | 2026 |
| Cardiff Drain Cleaning Company Limited | Extraterritorial | 2003 |
| Cardiff Drilling Ltd | Construction | 2025 |
| Cardiff Driveways & Patios Limited | Construction | 2024 |
| Cardiff Education Group Ltd | Education | 2023 |
| Cardiff Electrical & Construction Limited | Construction | 2014 |
| Cardiff Electrical Home Rewire Ltd | Construction | 2023 |
| Cardiff Electrical Services Ltd | Construction | 2022 |
| Cardiff Electricians Ltd | Construction | 2024 |
| Cardiff Elite Developments Ltd | Construction | 2020 |
| Cardiff Embroidery Company Limited | Wholesale & retail | 1999 |
| Cardiff Engineering Company Limited | Manufacturing | 2002 |
| Cardiff English Language Academy Limited | Education | 2017 |
| Cardiff Environmental Limited | Wholesale & retail | 2025 |
| Cardiff Estate Management Limited | Real estate | 2024 |
| Cardiff Estates & Lettings Limited | Real estate | 2003 |
| Cardiff European College Ltd | Education | 2025 |
| Cardiff Events & Decor Limited | Hospitality | 2024 |
| Cardiff Executive Travel Group Ltd | Transport & logistics | 2026 |
| Cardiff Extensions Ltd | Construction | 2021 |
| Cardiff Eyes Ltd | Health & social care | 2024 |
| Cardiff Fabrication and Welding Limited | Wholesale & retail | 2013 |
| Cardiff Fanzone Ltd | Hospitality | 2025 |
| Cardiff Fast Food Ltd | Hospitality | 2025 |
| Cardiff Financial Services Limited | Financial services | 2021 |
| Cardiff Fire Limited | Arts & recreation | 2023 |
| Cardiff Fish and Chips Limited | Hospitality | 2018 |
| Cardiff Fitness Limited | Arts & recreation | 2015 |
| Cardiff Flashing Fabrications Limited | | 1991 |
| Cardiff Food Limited | Hospitality | 2013 |
| Cardiff Foodbank | Other services | 2009 |
| Cardiff Fork Trucks Ltd | Wholesale & retail | 2021 |
| Cardiff Frame Company Limited | Manufacturing | 2003 |
| Cardiff Fresh Fish Ltd | Wholesale & retail | 2025 |
| Cardiff Friends for Pets Limited | Agriculture & fishing | 2017 |
| Cardiff Galvanizers (1969) Limited | Manufacturing | 1969 |
| Cardiff Galvanizers Holdings Limited | Professional & scientific | 1992 |
| Cardiff Garage Ltd | Wholesale & retail | 2020 |
| Cardiff Garden Room Ltd | Construction | 2021 |
| Cardiff GAS & Maintenance Ltd | Construction | 2020 |
| Cardiff Gemini Blinds Limited | Manufacturing | 2011 |
| Cardiff German Breakers Ltd | Wholesale & retail | 2025 |
| Cardiff German Specialists Limited | Wholesale & retail | 2022 |
| Cardiff Getaways Limited | Real estate | 2025 |
| Cardiff Gifts Ltd | Wholesale & retail | 2020 |
| Cardiff Glass Limited | Manufacturing | 1985 |
| Cardiff Golf Centre Ltd | Arts & recreation | 2004 |
| Cardiff Grand Thai Massage Limited | Other services | 2026 |
| Cardiff Greenview Garden Ltd | Real estate | 2018 |
| Cardiff Gynaecologists Limited | Health & social care | 2011 |
| Cardiff Hair and Beauty Ltd | Other services | 2020 |
| Cardiff Hair and Cosmetics Limited | Wholesale & retail | 2024 |
| Cardiff Hair Loss Clinic Ltd | Other services | 2023 |
| Cardiff Halal Foods Ltd | Wholesale & retail | 2026 |
| Cardiff Hand Surgery Limited | Health & social care | 2007 |
| Cardiff Handyman Ltd | Other services | 2025 |
| Cardiff Harlequins RFC Limited | Other services | 2016 |
| Cardiff Health Care Limited | Wholesale & retail | 2025 |
| Cardiff Heat Network Ltd | Manufacturing | 2021 |
| Cardiff Heating & Plumbing (South Wales) Ltd | Construction | 2018 |
| Cardiff Heating and Plumbing Limited | Construction | 2026 |
| Cardiff Holdings Ltd | Manufacturing | 2026 |
| Cardiff Holiday Homes Ltd | Hospitality | 2017 |
| Cardiff Holiday Lets Ltd | Hospitality | 2015 |
| Cardiff Home Investments Limited | Real estate | 2018 |
| Cardiff Home Services Ltd | Transport & logistics | 2025 |
| Cardiff Homes Ltd | Real estate | 2024 |
| Cardiff Hot TUB Hire Ltd | Administrative & support | 2024 |
| Cardiff House Clearance Limited | Other services | 2022 |
| Cardiff House Share Ltd | Real estate | 2023 |
| Cardiff Indian Kitchen Ltd | Hospitality | 2022 |
| Cardiff Indoor Flea Market Limited | Administrative & support | 2022 |
| Cardiff Innovations Limited | Professional & scientific | 2018 |
| Cardiff Institute for the Blind,(Incorporated)(The) | Information & communication | 1918 |
| Cardiff Insulation Company Ltd | Construction | 2026 |
| Cardiff Interiors Limited | Construction | 2024 |
| Cardiff International Film Festival Ltd | Information & communication | 2016 |
| Cardiff Islamic Centre CIC | Other services | 2021 |
| Cardiff Islamic Centre U.K. Limited | Education | 2022 |
| Cardiff IT Consultancy Ltd | Information & communication | 2019 |
| Cardiff J4L Ltd | Wholesale & retail | 2026 |
| Cardiff JET Ltd | Transport & logistics | 2021 |
| Cardiff K and Beauty Ltd | Other services | 2025 |
| Cardiff K Nails and Beauty Ltd | Other services | 2025 |
| Cardiff Keys Limited | Real estate | 2025 |
| Cardiff Land and House Limited | Professional & scientific | 2010 |
| Cardiff Land Estates Ltd | Real estate | 2022 |
| Cardiff Landlord Services Ltd | Administrative & support | 2019 |
| Cardiff Landscaping & Digger Services Ltd | Construction | 2022 |
| Cardiff Landscaping & Maintenance Services Limited | Arts & recreation | 2009 |
| Cardiff Language School Limited | Education | 2005 |
| Cardiff Laser and Survey Solutions Ltd | Manufacturing | 2025 |
| Cardiff Laser Limited | Manufacturing | 2025 |
| Cardiff Law Limited | Professional & scientific | 2017 |
| Cardiff Lifeguard Limited | Education | 2019 |