| Fozzilo Limited | Real estate | 2023 |
| Framezero Limited | Information & communication | 2021 |
| Fresco Take-Away Limited | Hospitality | 2019 |
| Full Fast Service Ltd | Wholesale & retail | 2025 |
| G J Commercials (UK) Ltd | Construction | 2014 |
| G. Andrews Windows & Doors Ltd | Other services | 2022 |
| Gapp Properties Ltd | Real estate | 2019 |
| Garlic 1 Ltd | Hospitality | 2026 |
| GD Offshore Limited | Professional & scientific | 2022 |
| GDM Rent Solutions Ltd | Real estate | 2025 |
| Gespra Lettings Limited | Hospitality | 2019 |
| Gespra Limited | Real estate | 2013 |
| Grays Steel Fabrication Limited | Manufacturing | 2018 |
| Greenough & Sons Roofing Contractors Ltd. | Construction | 1989 |
| Gwalchmai Hotel Limited | Hospitality | 2019 |
| Gwalia Service Station Ltd | Wholesale & retail | 2025 |
| Gwenfaen Limited | Agriculture & fishing | 1998 |
| Gwyliau Cymunod Holidays Ltd | Hospitality | 2022 |
| Gwynedd Life and Leisure Limited | Real estate | 1973 |
| Gwynfa Management Company Limited | Real estate | 1995 |
| Hall Electrical Ltd | Construction | 2023 |
| Hallswood Homes Ltd | Real estate | 2020 |
| Hamdden Limited | Hospitality | 2023 |
| Harbour Bar & Lounge Ltd | Real estate | 2013 |
| Heat & Screed (Anglesey) Limited | Construction | 2016 |
| Hefin Thomas Agri Contractors Limited | Water & waste | 2005 |
| Hello Wedding Ltd | Professional & scientific | 2025 |
| HEN Valley Commonhold Management Ltd | Households | 2021 |
| Henborth LLP | | 2026 |
| Hercules Products Limited | Professional & scientific | 2015 |
| Hermes Delivery Services Limited | Transport & logistics | 2025 |
| Highgate Publishing Limited | Arts & recreation | 2021 |
| Holly Molly Cafe Limited | Hospitality | 2026 |
| Holly Molly Kebab and Pizza Ltd | Hospitality | 2025 |
| Holyhead and Anglesey Weightlifting and Fitness Centre C.I.C. | Arts & recreation | 2011 |
| Holyhead Boatyard Limited | Transport & logistics | 2011 |
| Holyhead Deep Limited | Energy | 2016 |
| Holyhead Golf Shop Limited | Wholesale & retail | 2024 |
| Holyhead Holdings Ltd | Administrative & support | 2024 |
| Holyhead Holiday Homes Ltd | Hospitality | 2018 |
| Holyhead Hotspur Limited | Arts & recreation | 2024 |
| Holyhead Kebab & Pizza Limited | Hospitality | 2026 |
| Holyhead Kebabs Ltd | Hospitality | 2016 |
| Holyhead Maritime Museum Ltd | Arts & recreation | 1984 |
| Holyhead Masonic Hall Limited | Other services | 1995 |
| Holyhead Nails & Beauty Ltd | Other services | 2023 |
| Holyhead Pilotage Services Ltd. | Transport & logistics | 2018 |
| Holyhead Port Shipping Agency Ltd | Transport & logistics | 2023 |
| Holyhead Rugby Union Football Club Limited | Arts & recreation | 2014 |
| Holyhead Sailing Club C.I.C. | Hospitality | 2018 |
| Holyhead Tandoori Spice Ltd | Hospitality | 2025 |
| Hoofmanship Shop Limited | Wholesale & retail | 2022 |
| Hughes & Jones Limited | Agriculture & fishing | 2022 |
| Hughes Construction (Anglesey) Ltd | Construction | 2014 |
| Hughes Investments (Anglesey) Ltd | Construction | 2025 |
| I M Systems Limited | Manufacturing | 2025 |
| I. J. Ashworth Trading Ltd | Wholesale & retail | 2014 |
| Ingram Property Development Limited | Construction | 2003 |
| Ingram Property Holdings Limited | Financial services | 2003 |
| Injoy Consulting Ltd | Professional & scientific | 2015 |
| ION Utilities Ltd | Construction | 2025 |
| Island Print Company Limited | Manufacturing | 2025 |
| Istanbul 2023 Limited | Hospitality | 2023 |
| Ivanhoe Property Consulting Limited | Construction | 2022 |
| Ivanhoe Property Limited | Construction | 2011 |
| IVY House Properties Limited | Real estate | 2012 |
| J M Butchers Ltd | Wholesale & retail | 2025 |
| J Maguire Limited | Agriculture & fishing | 2025 |
| J&K Williams Services Ltd | Construction | 2021 |
| J.A.B Sailing Limited | Wholesale & retail | 2010 |
| Jade Doutch Holdings Ltd | Real estate | 2023 |
| Jameo’S Bar and Grill Ltd | Hospitality | 2023 |
| Jamie Parkes Plumbing & Heating Limited | Construction | 2022 |
| JCM Construction Anglesey Limited | Construction | 2021 |
| JCM Electrical Contractors Limited | Construction | 2021 |
| Jdem Works Ltd | Manufacturing | 2024 |
| Jerome Sillence Ltd | Other services | 2023 |
| Jido Properties LLP | | 2025 |
| JLH Electrical Ltd | Manufacturing | 2023 |
| JLW Holyhead Ltd | Wholesale & retail | 2021 |
| John Archer Carpets Limited | Wholesale & retail | 2020 |
| John Morgan & SON Plant Hire Limited | Construction | 2019 |
| Jones Financial Services (Anglesey) Ltd | Financial services | 2017 |
| JRG Fire Consultancy Ltd | Public administration | 2023 |
| JS Apparel Ltd | Wholesale & retail | 2025 |
| Justin Taylor Brickworks Limited | Construction | 2016 |
| KA KEI Limited | Real estate | 2025 |
| KB Transport Consultants Ltd | Transport & logistics | 2022 |
| Kingsmead Flats Management Company Limited | Households | 2026 |
| Landmark Surveys (North) Limited | Construction | 2017 |
| Levlaw (UK) Ltd | Other services | 2025 |
| Liberty Cambria CYF | Real estate | 2015 |
| Lisa M Ltd | Information & communication | 2003 |
| Little Bay (Rhoscolyn) Limited | Extraterritorial | 2010 |
| Llys Developments Ltd | Real estate | 2015 |
| LMW Electrical Contractors Ltd | Construction | 2023 |
| LON Porth Limited | Households | 2023 |
| Longford Road Dental Practice Ltd | Health & social care | 2013 |
| Looms Bros Ltd | Wholesale & retail | 2019 |
| Lotte Interiors Ltd | Wholesale & retail | 2025 |