| Fitness Tech Group Ltd | Information & communication | 2017 |
| Fitness Upgraded Limited | Arts & recreation | 2017 |
| Fitnessery Ltd | Wholesale & retail | 2015 |
| Fitology Kitchen Limited | Construction | 2017 |
| Fitorio Services Ltd | Wholesale & retail | 2021 |
| Fitter Body Ladies Cardiff Limited | Arts & recreation | 2022 |
| Fitterfx Global Limited | Financial services | 2021 |
| Fitters Rates Ltd | Construction | 2011 |
| Fitts Services Ltd | Information & communication | 2021 |
| Fiturpreneur Ltd | Education | 2020 |
| Fitwell Content Ltd | Other services | 2024 |
| Fitwins Limited | Arts & recreation | 2019 |
| Fitzalan Group Ltd | Wholesale & retail | 2025 |
| Fitzalan House (Cardiff) Limited | Real estate | 2018 |
| Fitzalan House Holdings (Cardiff) Limited | Financial services | 2026 |
| Fitzrail Services Ltd | Other services | 2018 |
| Fitzroy Trades Ltd | Wholesale & retail | 2017 |
| Fitzroy WSR Ltd | Real estate | 2025 |
| Five Beans Coffee Limited | Hospitality | 2026 |
| Five Coastguard Cottages Limited | Households | 1998 |
| Five Dog Technology Ltd | Information & communication | 2019 |
| Five Fields Restaurantt Limited | Hospitality | 2024 |
| Five Golden Rings Ltd | Professional & scientific | 2019 |
| Five Primary Elements Limited | Information & communication | 2021 |
| Five Property Limited | Real estate | 2018 |
| Five Star Chef Bryngarw House Ltd | Hospitality | 2013 |
| Five Star Cleaning Solutions Services Limited | Administrative & support | 2022 |
| Five Star Home Care Limited | Health & social care | 2014 |
| Five Star Investment Group Ltd | Wholesale & retail | 2025 |
| Five Star Removal Ltd | Transport & logistics | 2019 |
| Five Star Ventures Ltd | Wholesale & retail | 2024 |
| Five Stars Retail Limited | Wholesale & retail | 2019 |
| Fiveeightseven Events Ltd | Hospitality | 2026 |
| Fiveeightseven Ltd | Hospitality | 2024 |
| Fivesmiths Limited | Administrative & support | 2022 |
| Fivo Capital Limited | Manufacturing | 2013 |
| Fivora Cleaning Services Ltd | Administrative & support | 2025 |
| FIX 4 Cars Ltd | Wholesale & retail | 2019 |
| FIX and Give CIC | Wholesale & retail | 2026 |
| FIX Cardiff Ltd | Construction | 2025 |
| FIX UP 2 Look Sharp Barbers Ltd | Other services | 2026 |
| Fixaneed Ltd | Construction | 2021 |
| Fixarhost Ltd | Information & communication | 2024 |
| Fixfast Homes Ltd | Other services | 2025 |
| Fixing Point Holdings Limited | Financial services | 2022 |
| Fixmet Solutions Ltd | Information & communication | 2026 |
| Fixtech Solution Ltd | Wholesale & retail | 2019 |
| Fixtechuk Ltd | Construction | 2024 |
| Fixture Integration Limited | Health & social care | 2017 |
| Fixture Lettings Limited | Real estate | 2022 |
| Fiza Foods Ltd | Hospitality | 2019 |
| Fizoale Ltd | Wholesale & retail | 2025 |
| Fizzi Productions Limited | Arts & recreation | 2013 |
| Fizzyblox Ltd | Information & communication | 2016 |
| FJ Lowery & SON Properties Ltd | Real estate | 2023 |
| FJ Lowery & SON Roofing Ltd | Construction | 2009 |
| FJ Residential Limited | Administrative & support | 2017 |
| FJ Responsive Services Solution Limited | Construction | 2020 |
| Fj&Construction Ltd | Construction | 2025 |
| FJM Group Limited | Administrative & support | 2025 |
| FJM Limited | Health & social care | 2017 |
| Fjord Bathroom Ltd | Wholesale & retail | 2021 |
| FJP Builds UK Ltd | Construction | 2018 |
| FJQ Consulting Ltd | Professional & scientific | 2020 |
| FK J Trading Limited | Wholesale & retail | 2019 |
| FL Women and Family Wellness Community Interest Company | Education | 2020 |
| FLA Tech Devices Ltd | Wholesale & retail | 2022 |
| Flacom Ltd | Real estate | 2024 |
| Fladleys Ltd | Wholesale & retail | 2025 |
| Flair Enough Ltd | Hospitality | 2018 |
| Flambourne Property Management Ltd | Households | 2023 |
| Flame Cooling Limited | Manufacturing | 2015 |
| Flame Dance Studios Limited | Arts & recreation | 2019 |
| Flame Grill ELY Ltd | Hospitality | 2025 |
| Flame Interiors and Construction Ltd | Construction | 2020 |
| Flame Piri Piri Ltd. Ltd | Hospitality | 2026 |
| Flame Studios Limited | Arts & recreation | 2021 |
| Flameium Ltd | Manufacturing | 2025 |
| Flamesmart Ltd | Professional & scientific | 2022 |
| Flametree Aesthetics Ltd | Other services | 2018 |
| Flamewise Ltd | Energy | 2016 |
| Flamin' Grill N.I. Ltd | Hospitality | 2018 |
| Flaming BBQ Restaurant Ltd | Hospitality | 2019 |
| Flaming Frangos Ltd | Hospitality | 2025 |
| Flaming Wings Limited | Health & social care | 2022 |
| Flaming WOK Ltd | Hospitality | 2025 |
| Flamingo Build Ltd | Construction | 2018 |
| Flamingo Consultancy PVT Ltd | Information & communication | 2010 |
| Flamingo Fashion Ltd | Wholesale & retail | 2025 |
| Flamingo Grip Ltd | Information & communication | 2021 |
| Flamingo Productions Ltd | Arts & recreation | 2023 |
| Flamingo Resources Ltd | Construction | 2018 |
| Flanagan Labour Hire Ltd | Administrative & support | 2020 |
| Flare Hire Ltd | Administrative & support | 2024 |
| Flare Photovoltaic Solutions Limited | Wholesale & retail | 2026 |
| Flaremart Ltd | Wholesale & retail | 2024 |
| Flash Passive Fire Protection Ltd | Construction | 2025 |
| Flash Quality Plastering Ltd | Construction | 2025 |
| Flash Service Group Ltd | Wholesale & retail | 2023 |
| Flash SFX Ltd | Information & communication | 2022 |