| Field Digital Ltd | Information & communication | 2025 |
| Fieldgate Dock Management Limited | Households | 1990 |
| Fieldtech High Voltage Infrastructure Limited | Professional & scientific | 2011 |
| Fierza Roots Construction Ltd | Construction | 2024 |
| Fifteen Degrees Ltd | Wholesale & retail | 2016 |
| Fight and Grind Limited | Wholesale & retail | 2024 |
| FIGURE4 Limited | Construction | 2016 |
| Filby Construction Limited | Construction | 2022 |
| Filde Holdings Limited | Extraterritorial | 1998 |
| Filmtrain Limited | Professional & scientific | 2026 |
| Final Bell Ltd | Other services | 2025 |
| Financial Services 4 Schools Limited | Professional & scientific | 2008 |
| Finc Architects Ltd | Professional & scientific | 2013 |
| Finc Group Ltd | Education | 2021 |
| Finchley Tree Ltd. | Professional & scientific | 2021 |
| Findlay Macaskill Medical Services Limited | Health & social care | 2015 |
| Fine Content Ltd | Information & communication | 2025 |
| Fine Line Plastering Ltd | Construction | 2025 |
| Fine Security Services Ltd | Administrative & support | 2023 |
| Finemmy Ltd | Professional & scientific | 2025 |
| Finer Accountancy Ltd | Professional & scientific | 2022 |
| Finescale Models Limited | Manufacturing | 2014 |
| Finetrack Property Consultants Ltd | Professional & scientific | 2013 |
| Finguard Analytics Limited | Information & communication | 2025 |
| Finitor Holdings Limited | Financial services | 2020 |
| Finnamics Ltd | Information & communication | 2024 |
| Finset Limited | Financial services | 2020 |
| Finset Warranty Limited | Financial services | 2024 |
| Fintechaxis Limited | Administrative & support | 2020 |
| Fintechnicon Limited | Construction | 2022 |
| Fire Door Protection Limited | Construction | 2024 |
| Fire Tree (UK) Ltd | Administrative & support | 2011 |
| Firecare Fire Alarm Services Limited | Administrative & support | 2002 |
| Firecare Holdings Limited | Financial services | 2023 |
| Firefly Advisory Services Ltd | Professional & scientific | 2023 |
| Firestop Engineering Services Limited | Construction | 2017 |
| Firmament Education Limited | Education | 2014 |
| First Brand PLC | Transport & logistics | 1993 |
| First Call Construction Services Limited | Construction | 2019 |
| First Capital East Limited | Transport & logistics | 1988 |
| First City Recruitment Ltd | Administrative & support | 2016 |
| First City Recycling Ltd | Water & waste | 2024 |
| First Consult Care Limited | Health & social care | 2022 |
| First Consult Homes Limited | Real estate | 2023 |
| First Direct Marketing Solutions Ltd | Professional & scientific | 2018 |
| First Direct Solutions (UK) Limited | Professional & scientific | 2009 |
| First Essex Buses Limited | Transport & logistics | 1985 |
| First Fitness Ltd | Administrative & support | 2016 |
| First Kick Football Limited | Education | 2007 |
| First LET Properties Limited | Real estate | 2025 |
| First Phase Chiswick Limited | Information & communication | 2023 |
| First Phase Property (Horndon) Limited | Construction | 2023 |
| First Phase Property Limited | Construction | 2019 |
| First Point Aviation Ltd | Education | 2014 |
| First Spear Limited | Real estate | 2024 |
| First Stop Recruitment Services Limited | Administrative & support | 2015 |
| First Time Logic Ltd | Professional & scientific | 2023 |
| Firstbuilder Ltd | Construction | 2018 |
| Firstead Properties Limited | Real estate | 1966 |
| Firstmil Limited | Professional & scientific | 2017 |
| Fisguard Estates Ltd | Real estate | 2020 |
| Fisher Michael Secretaries Limited | Extraterritorial | 2000 |
| Fisher Property Group Ltd | Real estate | 2016 |
| Fisher Space PEN Company Limited | Wholesale & retail | 1999 |
| Fishpool Flooring Ltd | Construction | 2010 |
| Fisk Construction Ltd | Other services | 2020 |
| Fisk Consults Ltd | Professional & scientific | 2022 |
| Fisk Fire Maintenance Limited | Professional & scientific | 1998 |
| Fisk Fire Protection Limited. | Construction | 1998 |
| Fisk Group Hire Ltd | Other services | 2020 |
| Fisk Group Ltd | Construction | 2011 |
| Fisk Group Services Ltd | Other services | 2021 |
| Fisk Security Ltd | Extraterritorial | 2012 |
| Fit Snack LAB Ltd | Hospitality | 2025 |
| Fitclub Agency Limited | Administrative & support | 2023 |
| Fitcollectiv Limited | Professional & scientific | 2017 |
| Fitness Certified Ltd | Education | 2025 |
| Fitness for Committed Coaches Limited | Wholesale & retail | 2025 |
| Fits Group Ltd | Wholesale & retail | 2024 |
| Fits Holdings Ltd | Financial services | 2026 |
| Five Hundred Quid Limited | Extraterritorial | 2021 |
| Five Rivers Holding Group Limited | Financial services | 2022 |
| Five Years Time Ltd | Other services | 2026 |
| FIX a Boiler Limited | Manufacturing | 2021 |
| Fixent Construction Ltd | Construction | 2020 |
| Fixit Scaffolding Ltd | Administrative & support | 2017 |
| FJ Groundworks Limited | Construction | 2018 |
| FJ Holdings Limited | Financial services | 2023 |
| Flag in the Sand Lifestyle Limited | Administrative & support | 2014 |
| Flagstaff Point Limited | Professional & scientific | 2019 |
| Flagstone Financial Management Limited | Financial services | 2006 |
| Flanagans Taverns Limited | Hospitality | 2015 |
| Flash Electrical Solution Ltd | Energy | 2019 |
| Flash OUT Ltd | Other services | 2003 |
| Flash Point Design Limited | Professional & scientific | 2020 |
| Flat Care (Cricket) Limited | Households | 1975 |
| Flat Care (Old Mill) Limited | Households | 1985 |
| Flat Pack Friend Ltd | Construction | 2019 |
| Flats by Hortons Limited | Real estate | 2018 |
| Flats Global Ltd | Real estate | 2013 |