| Fitness Belfast Ltd | Arts & recreation | 2019 |
| Fitness Business CEO Limited | Professional & scientific | 2025 |
| Fitness Crown Ltd | Wholesale & retail | 2026 |
| Fitness Junkie Ltd | Real estate | 2016 |
| Fitness Quest Ltd | Arts & recreation | 2025 |
| Fitness Water Ltd | Hospitality | 2016 |
| Fitter Body Ladies Franchising NI Limited | Professional & scientific | 2023 |
| Fitzfilms Ltd | Information & communication | 2019 |
| Fitzrovia Mansion Limited | Households | 2009 |
| Fitzroy 100 Limited | Extraterritorial | 2012 |
| Fitzroy 104 Limited | Extraterritorial | 2012 |
| FITZROY10 Ltd | Financial services | 2020 |
| Fitzwilliam (Ascot) Holdings Limited | Financial services | 2019 |
| Fitzwilliam (Gylo) Holdings Limited | Financial services | 2019 |
| Fitzwilliam (Marylebone & Cotswolds) Holdings Limited | Financial services | 2020 |
| Fitzwilliam (President) Holdings Limited | Financial services | 2019 |
| Fitzwilliam (Waltham Forest) Holdings Limited | Financial services | 2019 |
| Fitzwilliam Clinic Belfast Limited | Health & social care | 2022 |
| Fitzwilliam Hotel (Belfast) Limited | Extraterritorial | 2008 |
| Fitzwilliam Management Company Limited | Households | 1999 |
| Fitzwilliam Trustees Number 1 Limited | Financial services | 2012 |
| Fitzwilliam Trustees Number 10 Limited | Financial services | 2019 |
| Fitzwilliam Trustees Number 11 Limited | Financial services | 2020 |
| Fitzwilliam Trustees Number 12 Limited | Financial services | 2020 |
| Fitzwilliam Trustees Number 2 Limited | Financial services | 2012 |
| Fitzwilliam Trustees Number 3 Limited | Financial services | 2019 |
| Fitzwilliam Trustees Number 4 Limited | Financial services | 2019 |
| Fitzwilliam Trustees Number 5 Limited | Financial services | 2019 |
| Fitzwilliam Trustees Number 6 Limited | Financial services | 2019 |
| Fitzwilliam Trustees Number 7 Limited | Financial services | 2019 |
| Fitzwilliam Trustees Number 8 Limited | Financial services | 2019 |
| Fitzwilliam Trustees Number 9 Limited | Financial services | 2019 |
| Five 156 Ltd | Administrative & support | 2023 |
| Five Caves Spirits Ltd | Wholesale & retail | 2025 |
| Five Percent Cafe Limited | Hospitality | 2018 |
| Five Pointz Pizza Ltd | Hospitality | 2025 |
| Five Star Commodities Ltd | Wholesale & retail | 2019 |
| FIVE-0 Consulting Ltd | Professional & scientific | 2023 |
| Fivemiletown Cheese Limited | Manufacturing | 2014 |
| Fivemiletown Creamery Limited | Manufacturing | 2014 |
| Fivepad Systems LP | | 2018 |
| Fivepenny Limited | Other services | 2025 |
| FIX a Gym Limited | Professional & scientific | 2012 |
| FIX to Go Belfast Ltd | Wholesale & retail | 2025 |
| Fixings Department Ltd | Wholesale & retail | 2021 |
| Fixit Physiotherapy & Training Ltd | Arts & recreation | 2021 |
| Fixtix Ltd | Information & communication | 2025 |
| Fizzblister Films Limited | Information & communication | 2019 |
| Fjcc Doran Properties Limited | Real estate | 2025 |
| FJH Capital Partners Ltd | Financial services | 2025 |
| FJJ Engineering Ltd | Professional & scientific | 2021 |
| FJJ Sports Management Ltd | Professional & scientific | 2016 |
| FJM Holdings Limited | Financial services | 2017 |
| FJM Logistics Ltd | Transport & logistics | 2020 |
| FJM Newco 2021 Limited | Financial services | 2021 |
| Fjordstrong Limited | Professional & scientific | 2019 |
| FJW the Vehicle Source Ltd | Wholesale & retail | 2025 |
| FK Lowry Holdings Limited | Construction | 2013 |
| FK Nnadi Ltd | Health & social care | 2024 |
| Fkcé Limited | Extraterritorial | 2023 |
| FL Education (UK) Limited | Education | 2015 |
| Flack Investments Limited | Real estate | 1999 |
| Flagship Bangor Ltd | Wholesale & retail | 2021 |
| Flagship Bangor Parking Ltd | Transport & logistics | 2021 |
| Flagship Holdings (N.I.) Limited | Financial services | 2013 |
| Flagship Internet Ltd | Information & communication | 2019 |
| Flagship Leisure Ltd | Extraterritorial | 2023 |
| Flagship Media Group Ltd | Manufacturing | 1996 |
| Flagship Newspapers Ltd | Manufacturing | 2019 |
| Flagship Web Design Ltd | Information & communication | 2019 |
| Flame City Limited | Hospitality | 2026 |
| Flame CUP Ltd | Hospitality | 2026 |
| Flanagan Art Ltd | Other services | 2007 |
| Flanagan Pharma Ltd | Wholesale & retail | 2009 |
| Flanagan Property & Investments Limited | Real estate | 2020 |
| Flanagan Sculpture Ltd | Arts & recreation | 2007 |
| Flanagan Surveying Limited | Professional & scientific | 2021 |
| Flannagan Media Ltd | Information & communication | 2020 |
| Flaschenpost Limited | Wholesale & retail | 2023 |
| Flashbar App LLP | | 2021 |
| Flat Management Services Limited | Households | 1989 |
| Flatxorn Trading Ltd | Hospitality | 2024 |
| Flavia Stelly Beauty Bar Ltd | Health & social care | 2025 |
| Flax & Teal Limited | Information & communication | 2013 |
| Flax Art Studios Ltd | Arts & recreation | 1993 |
| Flaxfield Woods Management Company Limited | Households | 2022 |
| Flaxhaus Ltd | Real estate | 2019 |
| Fleet Financial Limited | Wholesale & retail | 1996 |
| Fleet Fixation Ltd | Professional & scientific | 2022 |
| Fleetmentor Training Solutions Ltd | Education | 2025 |
| Fleetpay Billing Solutions Ltd | Administrative & support | 2026 |
| Fleming Liao Energy Consulting Ltd | Professional & scientific | 2023 |
| Fleming Training and Consultancy Services Limited | Education | 2014 |
| Flemish Bond Ltd | Real estate | 2021 |
| Fletcher Design Limited | Wholesale & retail | 2014 |
| Fletcher Property Management Ltd | Real estate | 2020 |
| Fletcher's Bistro Ltd | Hospitality | 2003 |
| Fletton Quays Hotel Ltd | Hospitality | 2017 |
| Fleurs DE Vincent (2022) Ltd | Wholesale & retail | 2022 |
| Fleurs DE Vincent Ltd | Wholesale & retail | 2020 |