| FD Comsol Ltd | Information & communication | 2025 |
| FDC Construction (N.I.) Limited | Construction | 2018 |
| FDI Intelligence Limited | Extraterritorial | 2001 |
| FDR Property Group Limited | Households | 2018 |
| FE Enterprises Ltd | Administrative & support | 2025 |
| FEB Secretaries Limited | Extraterritorial | 2001 |
| Federation for Ulster Local Studies Limited the | Arts & recreation | 1993 |
| Federation of Energy Response Aggregators Limited | Other services | 2020 |
| Federation of Family Practices East Belfast C.I.C. | Health & social care | 2014 |
| Federation of Family Practices North Belfast C.I.C. | Health & social care | 2015 |
| Federation of Family Practices South Belfast C.I.C. | Health & social care | 2015 |
| Federation of Family Practices West Belfast C.I.C. | Health & social care | 2014 |
| Federation of Women's Institutes of Northern Ireland | Other services | 2025 |
| Fedstone Limited | Real estate | 2020 |
| FEE Residential Ltd | Real estate | 2025 |
| Feed 365 Limited | Agriculture & fishing | 2016 |
| Feedback Mystery Shopping Limited | Professional & scientific | 2005 |
| Feeley's Interiors Limited | Wholesale & retail | 2020 |
| Feeney Electrical Limited | Construction | 1994 |
| Feet of Flames Limited | Information & communication | 2022 |
| Feet Street Podiatry Ltd | Health & social care | 2022 |
| Fegan Auto Repairs Limited | Wholesale & retail | 2021 |
| Feifei E Commerce Limited | Wholesale & retail | 2025 |
| Feile an Phobail Limited | Arts & recreation | 1995 |
| Feisfayre Limited | Manufacturing | 2016 |
| Feja Ltd | Health & social care | 2020 |
| FEL (NI) Limited | Professional & scientific | 2012 |
| Felbryn Studios Ltd | Manufacturing | 2024 |
| Fenestella Limited | Administrative & support | 1988 |
| Fenix Print & Design Ltd. | Manufacturing | 2025 |
| Fenix Solutions Ltd | Information & communication | 2005 |
| Fenser Limited | Real estate | 2021 |
| Fera Bakery Limited | Manufacturing | 2022 |
| Feral Pictures Ltd | Information & communication | 2024 |
| Ferdow Properties Ltd | Real estate | 2019 |
| Ferdow Properties NO2 Limited | Construction | 2021 |
| Ferdow Properties NO3 Limited | Real estate | 2026 |
| Ferful Place Limited | Real estate | 2023 |
| Fergal Holding Company Limited | Professional & scientific | 2009 |
| Ferguson Contracts Limited | Construction | 2016 |
| Ferguson Environmental Services Limited | Professional & scientific | 2014 |
| Ferguson Family Ventures Ltd | Hospitality | 2025 |
| Ferguson Hill Asset Management Ltd | Professional & scientific | 2013 |
| Ferguson Mccartan Ltd | Health & social care | 2008 |
| Ferguson Property Developments LLP | | 2006 |
| Ferien Acquisitions Holdings Limited | Financial services | 2024 |
| Ferien MIP Limited | Financial services | 2024 |
| Ferine Limited | Real estate | 2023 |
| Fern Computer Services Limited | Information & communication | 1979 |
| Fernagh Consultancy Ltd | Information & communication | 2019 |
| Fernagh Limited | Wholesale & retail | 2020 |
| Ferndene Dundonald Limited | Households | 2022 |
| Fernhill Properties (NI) Limited | Construction | 2005 |
| Fernleaf Systems Limited | Information & communication | 2013 |
| Fernmount Trading (N.I.) Ltd | Real estate | 2012 |
| Ferny Park Gardens Ltd | Households | 2019 |
| Ferran Port Services Limited | Transport & logistics | 1990 |
| Ferrari Stefania Ltd | Wholesale & retail | 2025 |
| Ferris Construction Ltd | Administrative & support | 2005 |
| Ferrosity Limited | Arts & recreation | 2008 |
| Ferry Court Developments Limited | Construction | 2003 |
| Festival Events Limited | Arts & recreation | 2024 |
| FET Investments Limited | Financial services | 2021 |
| Fetherstons Holdings Limited | Professional & scientific | 2026 |
| Fetherstons Limited | Real estate | 2020 |
| Fetherstons LM Limited | Real estate | 2026 |
| Feystown Investments Ltd | Real estate | 2025 |
| FF (IRL) Ltd | Transport & logistics | 2025 |
| FFC Fireaway Pizza Ireland Ltd | Hospitality | 2021 |
| FFC Ireland 1 Ltd | Hospitality | 2021 |
| FFC Ireland 2 Ltd | Hospitality | 2021 |
| FFC Ireland 3 Limited | Hospitality | 2021 |
| FFC WOK & Go Limited | Hospitality | 2021 |
| Ffff Ltd | Arts & recreation | 2021 |
| FFL Belfast Ltd | Arts & recreation | 2025 |
| FG Contracts Ltd | Construction | 2020 |
| Fgcd Ltd | Information & communication | 2026 |
| FGW Holdings Ltd | Professional & scientific | 2015 |
| FGW Property Ltd | Real estate | 2018 |
| FH Walton Ltd | Wholesale & retail | 2023 |
| FHC Property Investment Limited | Real estate | 2023 |
| Fhkj GOW Ltd | Wholesale & retail | 2024 |
| Fhrpng Limited | Wholesale & retail | 2024 |
| FIA Barber Shop Ltd | Other services | 2024 |
| FIA Business Investments Ltd | Real estate | 2022 |
| Fiacloir Feirste Limited | Health & social care | 2025 |
| Fianna Limited | Hospitality | 2018 |
| Fibe Accessories Ltd | Wholesale & retail | 2024 |
| Fibre Concrete Solutions Limited | Construction | 2019 |
| Fibre Contractors Ltd | Construction | 2020 |
| Fibre Health Ltd | Manufacturing | 2024 |
| Fibrus ISP (NI) Ltd | Information & communication | 2022 |
| Fibrus Ltd | Information & communication | 2018 |
| Fibrus Networks (Ffni) Ltd | Information & communication | 2020 |
| Fibrus Networks Ltd | Information & communication | 2012 |
| Fiction Dept Ltd | Wholesale & retail | 2026 |
| FIDELIS360 Limited | Professional & scientific | 2025 |
| Fido Developments Limited | Real estate | 2017 |
| Fido Marketing Ltd | Professional & scientific | 2022 |
| Field Bell Limited | Wholesale & retail | 2024 |