| Firs Court Management (Princes Risborough) Limited | Real estate | 1982 |
| First 2 Fit Consultancy Ltd | Other services | 2012 |
| First Cheer Limited | Administrative & support | 2011 |
| First Choice Carers Ltd | Public administration | 2021 |
| First Choice Drycleaners Limited | Other services | 2009 |
| First JET Ltd. | Administrative & support | 2023 |
| First Point Removals Ltd | Water & waste | 2025 |
| FIRST2COUNT Services Ltd | Other services | 2012 |
| FIRST4BUILDERS Limited | Construction | 2018 |
| Firstgate Residents Management Limited | Real estate | 1986 |
| Fit Gym Ltd | Arts & recreation | 2026 |
| FIT2GO Ltd | Education | 2025 |
| Fitness by Shakers Ltd | Health & social care | 2024 |
| Fitness Meets Lifestyle Limited | Arts & recreation | 2022 |
| FITNESS4X4 Ltd. | Information & communication | 2002 |
| Fitting Services Ltd | Construction | 2025 |
| Fitzalan Building and Roofing Ltd | Construction | 2023 |
| Five Oak Properties Ltd | Real estate | 2021 |
| Five Star Investments Limited | Real estate | 2018 |
| Five Star Travels and Tours Limited | Administrative & support | 2020 |
| FIX Motor Services Ltd | Wholesale & retail | 2025 |
| Fixer Therapies Ltd | Information & communication | 2024 |
| Flackwell Heath Moto Park Ltd | Arts & recreation | 2015 |
| Flagbearer Technologies UK Ltd | Information & communication | 2025 |
| Flareon Limited | Wholesale & retail | 2025 |
| Flash Film Transport Limited | Transport & logistics | 2008 |
| Flash Motor Parts Ltd | Wholesale & retail | 2024 |
| Flash Motors Ltd | Wholesale & retail | 2019 |
| Flavr Pockets Ltd | Hospitality | 2024 |
| Fleet Cost Management Limited | Professional & scientific | 2018 |
| Flegg Limited | Construction | 2018 |
| Fleks Solutions Limited | Administrative & support | 2020 |
| Flemming Associates Limited | Professional & scientific | 2012 |
| Flexdrive Rentals Ltd | Administrative & support | 2026 |
| Flexicare Partners Services Ltd | Health & social care | 2021 |
| Flexilux Stays Ltd | Hospitality | 2025 |
| Fleximark Limited | Real estate | 2002 |
| Flextnow Ltd | Information & communication | 2019 |
| Floccose Ltd | Wholesale & retail | 2020 |
| Floluxe Textiles Limited | Wholesale & retail | 2016 |
| Floodlighting Services Limited | Construction | 2016 |
| Floora Limited | Administrative & support | 2020 |
| Flowers by Post UK Limited | Wholesale & retail | 2023 |
| Flowers Make Sense Limited | Wholesale & retail | 2016 |
| Fluffy Hugs Ltd | Other services | 2025 |
| Flying Angel Limited | Health & social care | 1997 |
| FMA Management Ltd | Professional & scientific | 2014 |
| Fmash Foods Limited | Hospitality | 2025 |
| FME Limited | Professional & scientific | 2008 |
| FMM Autoclave Service Ltd | Manufacturing | 2013 |
| Focal Point.Music LDN Limited | Arts & recreation | 2026 |
| Fone Cloud Ltd | Wholesale & retail | 2013 |
| Fone Zone Limited | Other services | 2016 |
| Fonefix & Vape Ltd | Wholesale & retail | 2026 |
| Food Benna Ltd | Wholesale & retail | 2025 |
| Food Fusion Uxbridge Ltd | Hospitality | 2022 |
| Fooddies Enterprises Ltd | Wholesale & retail | 2026 |
| Foodi Distribution Limited | Wholesale & retail | 2022 |
| Foodie Bros Limited | Hospitality | 2024 |
| Fools on the Hill Collective Ltd | Information & communication | 2024 |
| Football FUN Factory - Community 127 Limited | Arts & recreation | 2024 |
| Footloose Performing Arts Ltd | Arts & recreation | 2026 |
| Footsteps Care Homes Limited | Health & social care | 2003 |
| Footsteps Care Limited | Health & social care | 2005 |
| Footsteps Care Outreach Limited | Health & social care | 2010 |
| Footsteps Education Limited | Education | 2013 |
| Footsteps Management Limited | Professional & scientific | 2013 |
| Footsteps Support Limited | Health & social care | 2013 |
| Fooyoung Garden Limited | Hospitality | 2024 |
| FOR Haven Sake Ltd | Health & social care | 2026 |
| Force Elec Ltd | Construction | 2022 |
| Forefront Estates Limited | Real estate | 2003 |
| Forelands Way Management Company Limited | Real estate | 1977 |
| Foremost Limited | Wholesale & retail | 2025 |
| Forever Eleven Consultancy Ltd | Information & communication | 2020 |
| Forever Toys Limited | Wholesale & retail | 2014 |
| Forster's Investments Ltd | Real estate | 2020 |
| Fort Trading and Marketing Limited | Wholesale & retail | 2001 |
| Fortem Information Technology Limited | Wholesale & retail | 2006 |
| Forthright Advisory and Consulting Limited | Professional & scientific | 2023 |
| Fortitude Performance Ltd | Arts & recreation | 2017 |
| Fortress London Limited | Construction | 2023 |
| Forttrading Properties Ltd | Real estate | 2018 |
| Fortunate Firm Limited | Wholesale & retail | 2021 |
| Fortune Flow Listers Ltd | Real estate | 2026 |
| Fortune Industries Limited | Wholesale & retail | 2010 |
| Fortune Travel & Tour Ltd | Administrative & support | 2025 |
| FORTY42TWO Limited | Manufacturing | 2018 |
| Forward Care London Ltd | Health & social care | 2016 |
| Fostering Innovations Limited | Health & social care | 2014 |
| Fostering Support Group Limited | Health & social care | 1989 |
| Found Once Limited | Information & communication | 2008 |
| Foundation of Hope Ltd | Health & social care | 2026 |
| Foundations Festival Ltd | Administrative & support | 2025 |
| Foundri Ltd | Professional & scientific | 2024 |
| Four Limited | Real estate | 2002 |
| Four Seasons Developments Ltd | Construction | 2024 |
| Fourem Housing Ltd | Real estate | 2025 |
| Fourteen Rochford Limited | Hospitality | 2019 |
| Fovia (Innovation) Limited | Extraterritorial | 2001 |