| Fintry Estates 2017 Ltd | Construction | 2017 |
| Fintry Estates Limited | Administrative & support | 2014 |
| Firebean Limited | Hospitality | 2015 |
| Firebird Therapies Ltd | Health & social care | 2026 |
| First Choice Auto Parts Ltd | Wholesale & retail | 2021 |
| First Fleet Services Limited | Transport & logistics | 2025 |
| First for Flowers Ltd | Wholesale & retail | 2012 |
| First for Fostering Ltd | Health & social care | 2019 |
| First Response Electrical Installations Ltd | Energy | 2014 |
| First Stop Darlington | Health & social care | 1998 |
| Firthmoor and District Community Association | Administrative & support | 2011 |
| Firthmoor Primary School | Education | 2012 |
| Fishers Cleaning Services Limited | Other services | 2004 |
| Fishlocks Estates Limited | Real estate | 2016 |
| Fisk Services Ltd | Transport & logistics | 2021 |
| Fit Fresh Limited | Hospitality | 2017 |
| Fit Fresh Meal Prep Ltd | Manufacturing | 2021 |
| Fitting Property Solutions Ltd | Manufacturing | 2020 |
| Five Star Shinies Ltd | Wholesale & retail | 2024 |
| FJ Machinery Ltd | Wholesale & retail | 2022 |
| FLA Inspection Limited | Professional & scientific | 2022 |
| Flashpost Ltd | Professional & scientific | 2017 |
| Flavours@Neasham Road Limited | Hospitality | 2025 |
| Flectusii Ltd | Real estate | 2018 |
| Fleet Managed Print Solutions Ltd | Wholesale & retail | 2010 |
| Fleet Road Property Management Ltd | Households | 2017 |
| Flintshire Buildings & DIY Centre Limited | Wholesale & retail | 2010 |
| FLO Estate Limited | Real estate | 2023 |
| Flocc Ltd | Professional & scientific | 2019 |
| Floorestore Commercial Limited | Construction | 2020 |
| Flooring Developments Limited | Construction | 2011 |
| Flooring Worx Limited | Wholesale & retail | 2017 |
| Florisoft Limited | Information & communication | 2006 |
| Flow Innovator Ltd. | Professional & scientific | 2022 |
| Flowers by Nattrass Ltd | Wholesale & retail | 2020 |
| FMG Repair Services Limited | Transport & logistics | 2004 |
| Food Hustle Ltd | Hospitality | 2022 |
| Food Plus NE Ltd | Hospitality | 2024 |
| Food Plus Store Ltd | Wholesale & retail | 2019 |
| Foods Darlington Ltd | Hospitality | 2014 |
| Foodsbymomi Limited | Hospitality | 2024 |
| FOR That Day Ltd | Real estate | 2021 |
| Forest Green Block 3 Management Limited | Households | 2006 |
| Forge Fit Ltd | Arts & recreation | 2019 |
| Formbook Limited | Information & communication | 2014 |
| Formulated Scale Limited | Information & communication | 2025 |
| Forster Plumbing & GAS Limited | Construction | 2015 |
| Forsyth House Limited | Real estate | 2015 |
| Forted Ltd | Information & communication | 2022 |
| Fortitude Design Alliance Limited | Professional & scientific | 2011 |
| Fortius Integrated Limited | Wholesale & retail | 2025 |
| FORTY1 NE Ltd | Hospitality | 2023 |
| Forward Motion Engineering Limited | Manufacturing | 2016 |
| Fotak Security Solutions Ltd | Administrative & support | 2025 |
| Found Consultancy Limited | Administrative & support | 2019 |
| Four Digital Solutions (Holdings) Limited | Wholesale & retail | 2020 |
| Four Digital Solutions Ltd | Wholesale & retail | 2011 |
| Foxhill Lodge RTM Company Limited | Households | 2013 |
| Foxy Wine Limited | Wholesale & retail | 2020 |
| FP Fire Protection Ltd | Construction | 2023 |
| Framedeck Limited | Construction | 2003 |
| Franchise Company International Limited | Professional & scientific | 2024 |
| Franciscommerce Limited | Wholesale & retail | 2025 |
| Franellie Science Ltd | Professional & scientific | 2023 |
| Free Spirit Kitchens Ltd | Manufacturing | 2026 |
| Freedom Kingdom Ltd | Professional & scientific | 2026 |
| Freemasons Hall (Darlington) Trading Limited | Hospitality | 2023 |
| Freemasons' Hall (Darlington) Limited | Other services | 2024 |
| Freeport IT Ltd | Information & communication | 2021 |
| FREIGHTFORWARD24H Ltd | Transport & logistics | 2025 |
| Frelion Ltd | Professional & scientific | 2022 |
| Fresh (Darlington) Limited | Hospitality | 2021 |
| Fresh (North East) Limited | Hospitality | 2026 |
| Fresh Cuts Barber Ltd | Other services | 2026 |
| Fresh Cuts Barber NE Limited | Other services | 2024 |
| Fresh Feethams Ltd | Hospitality | 2019 |
| Fresh Fishing LLP | | 2023 |
| Fretiller Investments Limited | Financial services | 2024 |
| Friern Barnet Management Limited | Households | 1998 |
| Frigate Group Limited | Construction | 2019 |
| Frontal Developments Ltd | Wholesale & retail | 2020 |
| Frontline MED Group Ltd | Education | 2026 |
| FRS Trading Ltd | Wholesale & retail | 2025 |
| FRY Capital Partners Forestry Limited | Extraterritorial | 2015 |
| FRY Capital Partners Limited | Extraterritorial | 2019 |
| FRY Capital Partners Renewable Energy Limited | Extraterritorial | 2014 |
| FRY Capital Partners Tech Limited | Extraterritorial | 2014 |
| FSL Properties Limited | Real estate | 2021 |
| FSR Global Ltd | Administrative & support | 2023 |
| Fuego Cakes Ltd | Hospitality | 2021 |
| Fuel Angel Limited | Extraterritorial | 2008 |
| Functional Rehabilitation Limited | Professional & scientific | 2024 |
| Funky Fidgets Shop Ltd | Wholesale & retail | 2021 |
| Funtool Ltd | Real estate | 2020 |
| Furfect Limited | Wholesale & retail | 2024 |
| Furfect Pet Store Ltd | Wholesale & retail | 2024 |
| Furness Commercial Consultants Limited | Professional & scientific | 2023 |
| Furniture Warehouse Yorkshire Limited | Wholesale & retail | 2014 |
| Fusion Joinery North East Limited | Construction | 2016 |
| Fusion Soultion Services Limited | Health & social care | 2008 |