| First Impressions Driveways (NE) Limited | Administrative & support | 2017 |
| First Impressions Property Services (UK) Limited | Administrative & support | 2012 |
| First JOB Ltd | Administrative & support | 2025 |
| First Response Industrial Supplies Limited | Manufacturing | 2015 |
| First Response Property Holdings Limited | Real estate | 2026 |
| First Steps Day Care (Stokesley) Ltd | Health & social care | 2015 |
| Firstcall Foods Limited | Hospitality | 2014 |
| Firtreekinloch Ltd | Transport & logistics | 2025 |
| Fish Byte Ltd | Hospitality | 2024 |
| Fish Point Limited | Wholesale & retail | 2025 |
| Fit Choice Ltd | Wholesale & retail | 2021 |
| Fitness Property Management Limited | Real estate | 2010 |
| Fitness With Lewis Limited | Other services | 2021 |
| Five Boys Ltd | Real estate | 2025 |
| Five Orange Pips Ltd | Hospitality | 2025 |
| Fivem Network Ltd | Information & communication | 2025 |
| FJ Piping Solutions Ltd | Professional & scientific | 2023 |
| FJB Safety Services Ltd | Extraterritorial | 2021 |
| FL (NE) Limited | Wholesale & retail | 2021 |
| Flagman Ltd | Extraterritorial | 2020 |
| Flagstart Limited | Wholesale & retail | 2003 |
| Flame Homes (NE) Ltd | Real estate | 2025 |
| Flames & Fizz Ltd | Manufacturing | 2016 |
| Flames Pizzeria N Ltd | Hospitality | 2026 |
| Flanges Ltd | Manufacturing | 2024 |
| Flannigan Holdings Ltd | Construction | 2025 |
| Flannigan Road Surfacing Ltd | Construction | 2025 |
| Flashcarsmboro Ltd | Wholesale & retail | 2025 |
| Flashpoint Photography Ltd | Professional & scientific | 2023 |
| Flat 3-26 GP LLP | | 2011 |
| Flat Stuff Limited | Real estate | 2018 |
| Flear Coaches Limited | | 1963 |
| Fleet Factors Limited | Wholesale & retail | 1975 |
| Fleetlease UK Limited | Administrative & support | 2008 |
| Fleetpro Limited | Wholesale & retail | 2009 |
| Fleur and MAE Limited | Wholesale & retail | 2026 |
| Flexpro Mobile Ltd | Wholesale & retail | 2020 |
| FLO Pilates Limited | Arts & recreation | 2023 |
| Flok F&B Ltd | Hospitality | 2025 |
| Flok Space Ltd | Hospitality | 2022 |
| Florah Furniture Limited | Manufacturing | 2024 |
| Florah Limited | Financial services | 2024 |
| Florea Achim Gheorghe Logistics Limited | Transport & logistics | 2025 |
| Florebright Care Ltd | Administrative & support | 2018 |
| Florebright Ltd | Professional & scientific | 2017 |
| Florin Ivancea Logistics Limited | Transport & logistics | 2026 |
| Florin Smart Cleaners Ltd | Administrative & support | 2026 |
| Florin's Barber Shop Ltd | Other services | 2024 |
| Flourish-Ed Training & Consultancy Ltd | Professional & scientific | 2026 |
| Flow Digital Ltd | Information & communication | 2013 |
| Flowerhouse at Linthorpe Limited | Wholesale & retail | 2019 |
| Flowers for YOU UK Ltd | Wholesale & retail | 2025 |
| Flowithic Ltd | Manufacturing | 2025 |
| Flowlify Ltd | Professional & scientific | 2025 |
| Flowtech Electrical Ltd | Manufacturing | 2025 |
| Fluid Engineering Solution Ltd | Construction | 2014 |
| Fluidvpn Ltd | Wholesale & retail | 2020 |
| Flush Fit Windows Ltd | Construction | 2025 |
| FLY With Abrar(Fwa) Limited | Administrative & support | 2025 |
| Fly-Safe Drone Solutions Ltd | Professional & scientific | 2018 |
| Flybee Travels Ltd | Administrative & support | 2025 |
| Flycutz Limited | Other services | 2025 |
| FM Base Limited | Information & communication | 2011 |
| FM Professional Ltd | Administrative & support | 2023 |
| FM Property Lettings Limited | Real estate | 2020 |
| FM Resumes Limited | Wholesale & retail | 2025 |
| FMC Insulation Services Ltd | Manufacturing | 2025 |
| FMH Construction Consultants Ltd | Construction | 2021 |
| FMH Development Limited | Households | 2026 |
| FMS Hind Limited | Real estate | 2025 |
| Fmttm.Fans.Net Limited | Information & communication | 2023 |
| FN Medica Ltd | Health & social care | 2025 |
| Fnamis Ltd | Wholesale & retail | 2025 |
| Fnvi Limited | Professional & scientific | 2014 |
| Fodders Limited | Construction | 2025 |
| Fojee Consulting Ltd | Information & communication | 2022 |
| Food Court Middlesbrough Limited | Hospitality | 2017 |
| Food Network Corporation Limited | Manufacturing | 2000 |
| Food Xpress Ltd | Hospitality | 2020 |
| Food Zone Boro Limited | Hospitality | 2025 |
| Food-Maestro Ltd | Hospitality | 2025 |
| Foodfix Ltd | Hospitality | 2023 |
| Foodgo Ltd | Hospitality | 2024 |
| Foodzone Middlesbrough Ltd | Hospitality | 2023 |
| Forbes Joinery & Interiors Ltd | Construction | 2022 |
| Fordham MAC Ltd | Administrative & support | 2019 |
| Forest Moon Film Ltd | Administrative & support | 2016 |
| Forever Changes Limited | Hospitality | 1995 |
| Forge Plus Limited | Professional & scientific | 2025 |
| Forrestal Engineering Ltd | Professional & scientific | 2024 |
| Forsyth K Limited | Wholesale & retail | 2014 |
| Forte Financial Consultancy Ltd | Professional & scientific | 2021 |
| Fortis Accountancy Services Limited | Professional & scientific | 2011 |
| Fortis Nexus Group Limited | Financial services | 2025 |
| Fortum Security Limited | Administrative & support | 2024 |
| Fortune Impex Limited | Wholesale & retail | 2025 |
| Fortune Reno Limited | Construction | 2025 |
| Forward Focus Consultancy Ltd | Other services | 2019 |
| Forward Focus Holdings Limited | Financial services | 2025 |
| Fosatica Ltd | Wholesale & retail | 2024 |