| First XI Limited | Herts | 2006 |
| First Yacht Administration Ltd | Woodbridge | 2022 |
| FIRST4MAGNETS Limited | Tuxford | 2016 |
| FIRST4SPARES UK Ltd | Manchester | 2011 |
| Firstaid Medics Limited | High Wycombe | 2025 |
| FIRSTAID4SPORT Limited | Poole | 2021 |
| Firstaidfordogs Ltd | London | 2016 |
| Firstbrite Co., Ltd | Cardiff | 2016 |
| Firstcentric Limited | Leeds | 2000 |
| Firstclass Staff Ltd | Canvey Island | 2008 |
| Firstclass Ventures Limited | Birmingham | 2016 |
| Firstforcosy Limited | Ramsgate | 2021 |
| Firstford (Sales) Limited | Hornchurch | 1993 |
| Firstford (Services) Limited | Hornchurch | 1993 |
| Firstplace Limited | London | 1980 |
| Firstport Investment Properties Limited | London | 2002 |
| Firstport Property Services NO 3 Limited | London | 2002 |
| Firstport Retirement Limited | London | 1997 |
| Firstport Secretarial Limited | London | 2006 |
| Firstrapid Residents Management Limited | Maidenhead | 1987 |
| Firstsing Ltd | Beckenham | 2023 |
| Firstslot Residents Management Limited | Wakefield | 1987 |
| Firstxtra Limited | Newbury | 2021 |
| Firtash Foundation | London | 2008 |
| Firth Candle Company Limited | Inverness | 2019 |
| Firth Carpets Limited | Birmingham | 1966 |
| Firth Cleveland Limited | Birmingham | 1953 |
| Firth Exhold Limited | York | 2026 |
| Firthcliffe 1958 Limited | Dewsbury | 2015 |
| Firthfair Ltd | Manchester | 2014 |
| Firwood Management Limited | Bury | 2021 |
| Fisborg Limited | Coventry | 2025 |
| Fiscal Forensics Limited | Macclesfield | 2020 |
| Fischer Commercial Limited | Leicester | 2015 |
| Fischer Dach & Fassaden Limited | London | 2020 |
| Fischer Energy PLC | Leicester | 2016 |
| Fischer Stien Limited | Harrogate | 2026 |
| Fischer United Limited | London | 2023 |
| Fish & Sea Ltd | London | 2026 |
| Fish 'R' Friends Limited | Manchester | 2021 |
| Fish 4 Life Ltd | Bristol | 2016 |
| Fish 4 Trials Limited | Aldershot | 1997 |
| Fish and Pond Ltd | Wolverhampton | 2017 |
| Fish Fuel Ltd | Falmouth | 2023 |
| Fish in Crewe Engineering Consultants Ltd | Cheshire | 1999 |
| Fish in Crewe Engineering Limited | Crewe | 2009 |
| Fish Media Group (East) Limited | St. Albans | 2009 |
| Fish Media Group (London) Limited | St. Albans | 2007 |
| Fish on Line Ltd | Bangor | 2014 |
| Fish on the Green Ltd | Wimbledon | 2024 |
| Fish Trans Ltd | Birmingham | 2018 |
| Fish Weisse & Ice Limited | Great Dunmow | 2015 |
| FISH4 Limited | Liverpool | 1995 |
| FISH4 Trading Limited | Liverpool | 2001 |
| FISH4CARS Limited | Liverpool | 2000 |
| FISH4JOBS Limited | Liverpool | 2000 |
| FISH6 Limited | Rotherham | 2005 |
| Fishbourne Quay Management Company Limited | London | 2011 |
| Fishburn Books Limited | London | 2006 |
| Fishele Limited | Edgware | 2024 |
| Fisher & Donaldson Limited | Cupar | 1957 |
| Fisher & Townsend (Funeral Directors) | Sutton Coldfield | 1963 |
| Fisher Automotive Limited | Birmingham | 2017 |
| Fisher Foundries Limited | Droitwich | 1914 |
| Fisher Haulage Limited | | 2004 |
| Fisher Michael Secretaries Limited | Chelmsford | 2000 |
| Fisher SVS Limited | Birmingham | 2016 |
| Fisher White Unlimited | Wembley | 2025 |
| Fishercast UK Limited | Welshpool | 2008 |
| Fisherman Fisheries Ltd | London | 2014 |
| Fisherman's Village Estate Limited | Eastbourne | 2001 |
| Fishersgate Limited | West Moors | 2017 |
| Fisherwick Mews Services Limited | Carrickfergus | 1989 |
| Fisherwood Road Limited | Alexandria | 2022 |
| Fishguard Bridge Limited | Cobham | 2003 |
| Fishguard Tunnel Limited | Cobham | 2003 |
| Fishstrip Limited | Pitlochry | 2016 |
| Fisika Ltd | Cranbrook | 2025 |
| Fisili Limited | Wakefield | 2008 |
| Fisk Designs Limited | Edinburgh | 2017 |
| Fisk Security Ltd | Chelmsford | 2012 |
| Fisknes Byggeservice Invest Limited | London | 2022 |
| Fisknes Byggeservice Limited | London | 2022 |
| Fissara Limited | Altrincham | 2023 |
| Fistral Bay Hotel Investments Limited | London | 2020 |
| Fit and FAB Coaching Ltd | Prenton | 2023 |
| Fit AYR Limited | Ayr | 2015 |
| Fit for Good Clothing Limited | Pulborough | 2019 |
| Fit for Good Training Limited | Pulborough | 2019 |
| Fit for Purpose Training Ltd | Bangor | 2024 |
| Fit for Sale Limited | Skipton | 2025 |
| Fit for Sport Limited | Wokingham | 1998 |
| Fit Minds Limited | High Wycombe | 2015 |
| Fit Nominee 2 Limited | London | 2013 |
| Fit Nominee Limited | London | 2012 |
| Fit OUT Finance Group Limited | Bordon | 2022 |
| Fit Precision Mold Co., Ltd | Beckenham | 2007 |
| Fit Products Limited | Amersham | 2019 |
| Fit Risk Management Ltd | Rochester | 2011 |
| FIT4GOLF Limited | Chepstow | 2012 |