| Firstaway Yacht Charters Ltd | Southampton | 2019 |
| Firstblood Entertainment Limited | Wembley | 2025 |
| Firstchants Purpose CIC | London | 2025 |
| Firstchoice Fitness Limited | Pontyclun | 2005 |
| Firsthand Collective Ltd | Bristol | 2025 |
| Firstland Estates Limited | Peterborough | 2003 |
| Firstlight on Demand Ltd | Bolton | 2018 |
| Firstmarch TV Limited | Blackpool | 2006 |
| Firstpastthepost Limited | Wigan | 2009 |
| Firstrobertson Limited | Arbroath | 2023 |
| Firstsite Limited | Colchester | 1994 |
| Firsttouchfootballcoaching Ltd | Newcastle Upon Tyne | 2025 |
| Firstwake Ltd | Bridgend | 2025 |
| Firth Park Boxing Academy CIC | Sheffield | 2026 |
| Firtree Swimming Ltd | Durham | 2025 |
| Firza Music Ltd | Sutton | 2024 |
| Fish and Duck Leisure Ltd | Ely | 2015 |
| Fish ARE Green Ltd | Waltham Abbey | 2025 |
| Fish Design Limited | Rossendale | 1998 |
| Fish File Storage Limited | Alcester | 1975 |
| Fish FRY Records Limited | Ramsgate | 2018 |
| Fish in a Dress Limited | Castle Cary | 2025 |
| Fish Island Social Hub CIC | London | 2025 |
| Fish Leisure Limited | Exeter | 2019 |
| Fish OUT of Water Events Limited | Lowestoft | 2011 |
| Fish POT Productions Limited | Buntingford | 2001 |
| Fish Shack at Rampart Ltd | Spalding | 2026 |
| Fish Tank Productions Ltd | London | 2016 |
| Fishbar Gallery Ltd | London | 2011 |
| Fishbone Design Limited | Bicester | 2000 |
| Fishbourne Padel Limited | Ashford | 2025 |
| Fishbowl Productions Limited | London | 2020 |
| Fishburn Sports Limited | London | 2019 |
| Fisher and Forge Ltd | Goole | 2025 |
| Fisher Dance Limited | Sutton-In-Ashfield | 2017 |
| Fisher Harrison Limited | Woodstock | 2019 |
| Fisher Holdings Limited | Richmond | 2015 |
| Fisher X Ltd | Reading | 2026 |
| Fisheries Inn Angling Society Limited | Northwood | 2020 |
| Fisherman Musical (Rights) Limited | London | 2021 |
| Fishermansfortune Ltd | Liverpool | 2024 |
| Fisherrow Ltd | Musselburgh | 2012 |
| Fishers Green Sailing Club CIC | Bishop'S Stortford | 2013 |
| Fishery Management (UK) Ltd | London | 2009 |
| Fishguard and Goodwick Rugby Football Club Limited | Fishguard | 2022 |
| Fishguard Festival of Music Gwyl Gerdd Abergwaun Ltd | Crymych | 1986 |
| Fishguard Invasion Centre Trust Limited | Goodwick | 1998 |
| Fishing 4 Chips Ltd | Northampton | 2023 |
| Fishing Around the UK CIC | Edinburgh | 2026 |
| Fishing London Ltd | London | 2015 |
| Fishing Maniacs Limited | Brentwood | 2020 |
| Fishing Scotland Limited | Edinburgh | 1999 |
| Fishingtripper Ltd | Saffron Walden | 2025 |
| Fishpeople Ltd | London | 2024 |
| Fishpix Limited | Newcastle Under Lyme | 2005 |
| Fishub Ltd | Maidenhead | 2025 |
| Fisikal Limited | Wallingford | 2008 |
| Fiso Club Limited | London | 2003 |
| Fiso Limited | Bury St. Edmunds | 2000 |
| Fison Fitness Ltd | Fordingbridge | 2014 |
| Fist Club Wrestling Ltd | Bury St. Edmunds | 2026 |
| Fist Design Ltd | Farnborough | 2019 |
| Fistral Beach Ltd | Truro | 2004 |
| Fistral Stereo Ltd | Newquay | 2025 |
| Fit & FAB Limited | London | 2016 |
| Fit & Food Limited | London | 2021 |
| Fit & FUN 4 Everyone Limited | Mitcham | 2023 |
| Fit 100 Limited | Marlborough | 2017 |
| Fit 2 Box Ringwood Limited | Ferndown | 2025 |
| Fit 2 Fight MMA UK Limited | Slough | 2021 |
| Fit 2 U Limited | Ilford | 2025 |
| Fit 30 Limited | Olney | 2017 |
| Fit 4 Force C.I.C. | Liversedge | 2011 |
| Fit 4 Kidz (UK) | London | 2012 |
| Fit 4 Life (Ackworth) Limited | Doncaster | 2015 |
| Fit 4 Purpose (Angus) Ltd | Carnoustie | 2011 |
| Fit and FLY Limited | Bexleyheath | 2017 |
| Fit and Happy Limited | Edinburgh | 2018 |
| Fit and Healthy Ltd | Sidcup | 2019 |
| Fit and Healthy Mums Ltd | Abingdon | 2017 |
| Fit and Well Limited | Pontypridd | 2014 |
| Fit AS Gym Ltd | Stockport | 2025 |
| Fit AS PT Ltd | London | 2021 |
| Fit AS Studio Fitness Limited | Portsmouth | 2022 |
| Fit AS YOU Go Ltd | London | 2026 |
| Fit Birds Limited | Bromley | 2020 |
| Fit Bodies Gym & Fitness Ltd | Leek | 2018 |
| Fit Body Farm Ltd | Kilmarnock | 2015 |
| Fit Body Formula Ltd | Worthing | 2012 |
| Fit Body in 6 Limited | Fleet | 2016 |
| Fit Body Training Ltd | Derby | 2024 |
| Fit Body Transformation Ltd | Tamworth | 2023 |
| Fit Bont 2.0 Ltd | Abertawe | 2025 |
| Fit Bont Limited | Pontarddulias | 2018 |
| Fit Box Clubs Ltd | Birmingham | 2019 |
| Fit by Domenica Ltd | London | 2024 |
| Fit by Lauren J Ltd | Enniskillen | 2022 |
| Fit by Simona Limited | Leicester | 2022 |
| Fit Chiswick & Shepherds Bush Ltd. | London | 2018 |
| Fit Chiswick Ltd | London | 2022 |