| Cardiff Lifestyle Medicine Ltd | Health & social care | 2025 |
| Cardiff Lift Company Limited | Manufacturing | 1991 |
| Cardiff Lift Holdings Limited | Financial services | 2023 |
| Cardiff Living Ltd | Real estate | 2023 |
| Cardiff Lock & Safe Company Limited | Other services | 1985 |
| Cardiff Lounge Ltd | Hospitality | 2023 |
| Cardiff Luckey Letting Limited | Real estate | 2013 |
| Cardiff M.A.D.E C.I.C. | Wholesale & retail | 2013 |
| Cardiff Management Solutions Ltd | Professional & scientific | 2012 |
| Cardiff Marble & Terrazo Company Limited | Manufacturing | 1987 |
| Cardiff Marble Limited | Manufacturing | 2010 |
| Cardiff Martial Arts Academy Limited | Arts & recreation | 2011 |
| Cardiff Martial Arts Limited | Arts & recreation | 2005 |
| Cardiff Masonic Hall Company Limited(The) | Hospitality | 1894 |
| Cardiff Mechanical Services Ltd | Construction | 2022 |
| Cardiff Medical Consulting Limited | Health & social care | 2017 |
| Cardiff Medical Events Ltd | Professional & scientific | 2019 |
| Cardiff Medical Sports and Social Club Limited | Hospitality | 2013 |
| Cardiff Merchandising Limited | Wholesale & retail | 2016 |
| Cardiff MET Students' Union | Education | 2009 |
| Cardiff Metal Merchants Limited | Wholesale & retail | 2008 |
| Cardiff Metropolitan University Football Club Limited | Arts & recreation | 2024 |
| Cardiff Mini Market Ltd | Wholesale & retail | 2026 |
| Cardiff Mini Mart Ltd | Wholesale & retail | 2025 |
| Cardiff Mobile Zone Ltd | Wholesale & retail | 2026 |
| Cardiff Modern Living Management Ltd | Real estate | 2024 |
| Cardiff Montessori Outreach Limited | Education | 2022 |
| Cardiff Mortgage Centre Ltd | Financial services | 2011 |
| Cardiff MOT & Repair Ltd | Wholesale & retail | 2010 |
| Cardiff MOT Centre Ltd | Wholesale & retail | 2020 |
| Cardiff MOT Ltd | Wholesale & retail | 2023 |
| Cardiff Motor Auctions Ltd | Wholesale & retail | 2023 |
| Cardiff Motorcycles Limited | Wholesale & retail | 2006 |
| Cardiff Movers Limited | Transport & logistics | 2024 |
| Cardiff Mower Services Limited | Wholesale & retail | 2002 |
| Cardiff Multi Speciality Clinic and Diagnostics Limited | Health & social care | 2022 |
| Cardiff MUM Limited | Administrative & support | 2023 |
| Cardiff Music History CIC | Administrative & support | 2024 |
| Cardiff Neptune Court Management Limited | Real estate | 2011 |
| Cardiff Netball Arena Ltd | Hospitality | 2025 |
| Cardiff North Dementia Service CIC | Other services | 2023 |
| Cardiff Office Furniture Limited | Construction | 2002 |
| Cardiff Olympic Gymnastics | Arts & recreation | 2008 |
| Cardiff One Properties Ltd | Real estate | 2025 |
| Cardiff Orangeries Ltd | Professional & scientific | 2010 |
| Cardiff Oratory Ltd | Hospitality | 2017 |
| Cardiff Pain & Performance Ltd | Health & social care | 2019 |
| Cardiff Panda Letting Ltd | Real estate | 2026 |
| Cardiff Parkway Developments Limited | Real estate | 2016 |
| Cardiff Parkway Station Limited | Construction | 2018 |
| Cardiff Part Exchange Center Ltd | Extraterritorial | 2019 |
| Cardiff Partnership Fund Limited | Professional & scientific | 1999 |
| Cardiff Payroll Services Ltd | Professional & scientific | 2025 |
| Cardiff People First | Education | 2002 |
| Cardiff Permanent Makeup Studio Limited | Other services | 2020 |
| Cardiff Personal Training Studio Limited | Arts & recreation | 2017 |
| Cardiff Pest Control Limited | Information & communication | 2024 |
| Cardiff Pet Cremation Ltd | Other services | 2023 |
| Cardiff Phones & Tech Repairs Limited | Manufacturing | 2025 |
| Cardiff Physiotherapy Clinic Ltd | Health & social care | 2025 |
| Cardiff Pilates Studio Ltd | Other services | 2023 |
| Cardiff Pitched Roofing Ltd | Construction | 2024 |
| Cardiff Pizza Company Limited | Hospitality | 2025 |
| Cardiff Plumbing Contractors Ltd | Construction | 2024 |
| Cardiff Plumbing Limited | Construction | 2025 |
| Cardiff Plumbing Management Ltd | Construction | 2011 |
| Cardiff Pointe Estates Ltd | Real estate | 2025 |
| Cardiff Pool Club Limited | | 1982 |
| Cardiff Post Production CYF. | Information & communication | 2018 |
| Cardiff Pottery Workshops Foundation CIC | Education | 2017 |
| Cardiff Poultry Ltd | Wholesale & retail | 2014 |
| Cardiff Powder Coaters Limited | Manufacturing | 2013 |
| Cardiff Power Limited | Real estate | 2003 |
| Cardiff Process Contracting (CPC) Electrical Services Ltd | Construction | 2002 |
| Cardiff Productions Limited | Information & communication | 2015 |
| Cardiff Project Development Ltd | Construction | 2024 |
| Cardiff Prop Co Limited | Real estate | 2024 |
| Cardiff Properties Ltd | Real estate | 2018 |
| Cardiff Properties Management Ltd | Other services | 2018 |
| Cardiff Property Corporation Limited | Real estate | 2009 |
| Cardiff Property Group Ltd | Real estate | 2023 |
| Cardiff Property Investment Ltd | Real estate | 2015 |
| Cardiff Property Lettings Limited | Real estate | 2004 |
| Cardiff Property Maintenance Ltd | Construction | 2023 |
| Cardiff Property Management Ltd | Real estate | 2010 |
| Cardiff Property Management SW Ltd | Households | 2023 |
| Cardiff Property Services Ltd | Construction | 2026 |
| Cardiff Queer Orchestra CIC | Arts & recreation | 2025 |
| Cardiff Railway Company Limited | Arts & recreation | 2017 |
| Cardiff Ready Mixed Concrete Ltd | Construction | 2006 |
| Cardiff Remap Ltd | Wholesale & retail | 2019 |
| Cardiff Remedy Centre Limited | Health & social care | 2016 |
| Cardiff Rescue Ltd | Wholesale & retail | 2011 |
| Cardiff RIB Hire Ltd | Wholesale & retail | 2019 |
| Cardiff Roof Cleaning Ltd | Administrative & support | 2023 |
| Cardiff Roofing Limited | Construction | 2022 |
| Cardiff Rugby Club Limited | Arts & recreation | 2019 |
| Cardiff Rugby Football Club Limited | Arts & recreation | 2003 |
| Cardiff Salad Garden C.I.C. | Agriculture & fishing | 2017 |
| Cardiff Scaffolding Contracts Limited | Construction | 2007 |