| Fizakrafts Limited | Manchester | 2021 |
| Fizz Clothing Company Limited | Cheshire | 1993 |
| Fizz Group Limited | Solihull | 2015 |
| Fizz Marketing Ltd | Penryn | 2023 |
| Fizzy Bubbler Limited | London | 2010 |
| Fizzy Ducks Ltd | Blackpool | 2014 |
| Fizzy Tarte Ltd | Ulverston | 2011 |
| Fizzydo Limited | Market Harborough | 2021 |
| FJ Property Maintenance Limited | Newcastle Upon Tyne | 2009 |
| Fjalla Ltd | Worcester | 2023 |
| FJB Safety Services Ltd | Middlesbrough | 2021 |
| Fjeld Invest Limited | London | 2010 |
| Fjeld Mekaniske Limited | London | 2022 |
| Fjell Luft Retreat Holding Limited | London | 2024 |
| Fjell Luft Retreat Limited | London | 2024 |
| Fjellstad Global Limited | London | 2007 |
| FJF Limited | Halesowen | 2000 |
| FJM International Limited | Oldham | 1999 |
| Fjmg Ltd | London | 2022 |
| FJP Investment Ltd | Whetstone | 2013 |
| FK ALL Trading Ltd | Styal | 2023 |
| FK Intrade Co., Ltd | London | 2008 |
| FK Payroll Invest Ltd | Dover | 2023 |
| FK Payroll Ltd | Dover | 2023 |
| FK7 Indoor Wash Ltd | Stirling | 2021 |
| Fkcé Limited | Belfast | 2023 |
| Fkfibre Ltd | Doncaster | 2022 |
| FKG (UK) Corporation Limited | London | 2006 |
| FKM Business Consultant UK Ltd | Oban | 2024 |
| Fkst Limited | Finchley | 1997 |
| FL Estates Limited | St Neots | 2022 |
| FL1NG Limited | Harrogate | 2020 |
| FLA Academy Limited | Accrington | 2021 |
| Flackford Ltd | Salford | 2014 |
| Flackfri Stad OCH Flytt Limited | London | 2022 |
| Fladby Limited | London | 2007 |
| Fladder & Co Limited | London | 2024 |
| Flag Brand Products Limited | Burnham On Crouch | 2004 |
| Flag Locum Services Limited | Milton Keynes | 2004 |
| Flag Stitch and Design Ltd. | Southminster | 2002 |
| Flagbright Limited | London | 1983 |
| Flagdor Limited | Dunfermline | 2021 |
| Flagmakers Limited | Chesterfield | 2009 |
| Flagman Ltd | Middlesbrough | 2020 |
| Flagpoles Limited | Newton Aycliffe | 1993 |
| Flags Express Limited | Ilkeston | 2010 |
| Flagship Leisure Ltd | Belfast | 2023 |
| Flagships Limited | London | 2003 |
| Flagstaff Lodge Ltd | Newry | 2025 |
| Flagsun Green Power Co., Ltd | Beckenham | 2014 |
| Flagum Ltd | London | 2018 |
| Flairfield Trading Limited | London | 2005 |
| Flambeau Limited | London | 2013 |
| Flame and Frame Limited | Chatham | 2025 |
| Flame and Thunder Two Ltd | Manchester | 2025 |
| Flame Holdings Ltd | Smethwick | 2021 |
| Flame Insulation Resistant Engineering Ltd | Wigan | 2022 |
| Flame Limited | Watford | 2018 |
| Flame Rise Capital Partners Ltd | Manchester | 2026 |
| Flamefast Education Limited | Warrington | 2013 |
| Flamefast Fire Ltd | Warrington | 2019 |
| Flamefast GAS Solutions Ltd | Warrington | 2019 |
| Flamepro Textiles Limited | Neyland, Milford Haven | 2006 |
| Flameshield Limited | Fareham | 2017 |
| Flaming Bear Limited | Hove | 2017 |
| Flamingo 6 Ltd | Newcastle Upon Tyne | 2023 |
| Flamingo Shot Ltd | Manchester | 2023 |
| Flammable Ice Limited | Salisbury | 2011 |
| Flammable Records UK Limited | Salisbury | 2011 |
| Flamstead Farm Management Limited | Chesham | 2005 |
| Flanagan Sales Limited | Preston | 2012 |
| Flanchford Farm Limited | Reigate | 2015 |
| Flange Paint Technology Co., Ltd | London | 2018 |
| Flapres Limited | London | 2007 |
| Flarkens Alltjanst Limited | London | 2025 |
| Flas 002 Ltd | Kings Langley | 2020 |
| Flas 003 Ltd | Kings Langley | 2020 |
| Flas 004 Ltd | Kings Langley | 2020 |
| Flas 005 Ltd | Kings Langley | 2020 |
| Flas 006 Ltd | Kings Langley | 2020 |
| Flas 007 Ltd | Kings Langley | 2020 |
| Flas 008 Ltd | Kings Langley | 2020 |
| Flash Body Inspirations Ltd | Colchester | 2011 |
| Flash Creative Ltd | London | 2018 |
| Flash Digital Media Limited | Glasgow | 2013 |
| Flash NO. 1 Limited | Sheffield | 1969 |
| Flash NO. 2 Limited | Sheffield | 1986 |
| Flash NO. 3 Limited | Sheffield | 1921 |
| Flashatom Ltd | Cambridge | 2021 |
| Flashforge Entertainment Ltd | London | 2026 |
| Flashgard Limited | Sheffield | 2021 |
| Flashlightarts Productions Limited | Leyton | 2012 |
| Flashpark Limited | London | 2007 |
| Flat OUT (Nottingham) Limited | West Yorkshire | 2002 |
| Flat Pack Living Ltd | Portsmouth | 2017 |
| Flat Rock Management Company Ltd | Bangor | 2019 |
| Flat Roofing Systems Ltd | Hadlow | 2014 |
| Flatball Limited | Clitheroe | 2002 |
| Flatform Shoes and Sandals Limited | Felixstowe | 2017 |
| Flatform Shoes Limited | Felixstowe | 2017 |