| 2W Limited | Professional & scientific | 2006 |
| Adgo Machinery Ltd | Wholesale & retail | 2017 |
| Agricloud Limited | Information & communication | 2019 |
| Agrinet Ltd | Professional & scientific | 2019 |
| AJ Anglesey Lettings Ltd | Real estate | 2025 |
| Amlwch Dental Practice Ltd | Health & social care | 2021 |
| Anglesey Aerials Limited | Wholesale & retail | 2008 |
| Anglesey Boat Company Limited | Real estate | 1980 |
| Anglesey Bouncy Castle Hire Limited | Administrative & support | 2013 |
| Anglesey Car Care Ltd | Wholesale & retail | 2024 |
| Anglesey Events Ltd | Administrative & support | 2017 |
| Anglesey Golf Club,Limited | Arts & recreation | 1914 |
| Anglesey Lettings Management Ltd | Real estate | 2022 |
| Anglesey Lobster Company Ltd | Agriculture & fishing | 2006 |
| Anglesey Masonry Ltd. | Mining & quarrying | 2003 |
| Anglesey Riding Center Ltd | Education | 2025 |
| Anglo Canadian Exploration (Ace) Limited | Mining & quarrying | 1973 |
| Atal Music Limited | Information & communication | 2000 |
| Bagnol Holiday Parks Limited | Hospitality | 2023 |
| Baron Hill Golf Club Limited | Arts & recreation | 1995 |
| BCD Grass Converters Limited | Agriculture & fishing | 2019 |
| Benllech Builders Limited | Construction | 2022 |
| Bico Limited | Manufacturing | 1956 |
| Bingham Rawlings Partnership Limited | Construction | 2006 |
| Bodorgan Environmental Management Limited | Real estate | 1999 |
| Bodorgan Marine Ltd | Agriculture & fishing | 2022 |
| Bodowen Farms Limited | Agriculture & fishing | 1965 |
| Born & Bred Welsh Black Ltd | Agriculture & fishing | 2018 |
| Bron Menai Limited | Real estate | 2024 |
| C-Search Limited | Extraterritorial | 2012 |
| Cadnant Properties Limited | Real estate | 2004 |
| Caer Glaw Ltd | Mining & quarrying | 2021 |
| Cambrian Projects Ltd | Real estate | 2007 |
| Complete Miniature Railways Limited | Manufacturing | 2002 |
| Condessa H.P.C. Company Limited | | 1976 |
| Dafarn Rhos Limited | Hospitality | 2003 |
| Dantech Engineering Solutions Ltd | Professional & scientific | 2009 |
| DDS Aero Limited | Transport & logistics | 2001 |
| Doran Builders (Anglesey) Limited | Construction | 2006 |
| Dragon Games Limited | Wholesale & retail | 2024 |
| Drome Self-Serve Limited | | 1988 |
| Dyfed HUW Williams CYF | Households | 2025 |
| E & SF Williams Ltd | Professional & scientific | 2016 |
| Electrical Supplies (Anglesey) Limited | Wholesale & retail | 1972 |
| Elen Pritchard CYF | Hospitality | 2021 |
| Elim Citroen Limited | Wholesale & retail | 2014 |
| Elim Peugeot Limited | Wholesale & retail | 2014 |
| Eryri Limited | Arts & recreation | 1998 |
| Ezyherb Ltd | Manufacturing | 2010 |
| Farrar Courier Ltd | Transport & logistics | 2026 |
| Forrest-Owen Group Ltd | Administrative & support | 2014 |
| Funsport Rhosneigr Limited | Wholesale & retail | 2003 |
| GC Group Holdings Limited | Financial services | 2024 |
| GH Grass Converters Limited | Agriculture & fishing | 2018 |
| Gina Equestrian Ltd | Other services | 2025 |
| Glyn Garth Court Flats Limited | Real estate | 1965 |
| Good BYE Bill Limited | | 1977 |
| Gora Geomatics Ltd | Professional & scientific | 2025 |
| Grass Converters Limited | Agriculture & fishing | 2009 |
| Gwasanaethau Wennol Services CYF | Agriculture & fishing | 2005 |
| Gwyndy Ltd | Real estate | 2025 |
| H & M Services | | 1999 |
| H Dean Limited | Hospitality | 1990 |
| H. C. D. Properties Ltd. | Hospitality | 1999 |
| Habitat and Wildlife Conservation Society (Hawcs) | Administrative & support | 2009 |
| Harela's Ltd | Hospitality | 2021 |
| Harte Aviation Search Consultants Ltd | Construction | 2024 |
| Highway Analytics Ltd | Professional & scientific | 2014 |
| Hold My Data Limited | Information & communication | 2026 |
| Holdco 181 Limited | Administrative & support | 2021 |
| Holyhead Golf Club,Limited(The) | Arts & recreation | 1950 |
| Holyhead Marina Limited | Other services | 1995 |
| Holyhead Marine Services Limited | Manufacturing | 1967 |
| Holyhead Towing Company Limited | Transport & logistics | 1966 |
| Holyhead Towing Group Limited | Professional & scientific | 1962 |
| Humphreys Waste Recycling Ltd | Water & waste | 2015 |
| HUW Maldwyn Williams Ltd | Professional & scientific | 2017 |
| Huws Eugrad Developments CYF | Construction | 2001 |
| Hyland Residential Home Limited | Health & social care | 2006 |
| I H & D H Williams Limited | Construction | 2005 |
| Industrial & Commercial Building Design Ltd. | Professional & scientific | 1998 |
| Island Fire Doors Ltd | Public administration | 2024 |
| J.A.C. Scaffolding Ltd | Construction | 2025 |
| J.Parry & Hughes Limited | Construction | 1963 |
| Jet&Co Limited | Administrative & support | 2014 |
| John Kelly Construction Services Limited | Construction | 2008 |
| Jones Associates Servicing Ltd. | Financial services | 2003 |
| Jwetv Limited | Information & communication | 2014 |
| LEE Summers Roofing Ltd | Construction | 2025 |
| Lewis Forecourts Limited | Wholesale & retail | 1997 |
| LON Y Dryw Limited | Households | 2018 |
| Maitland Installations Ltd | Construction | 2006 |
| Menai Windows Limited | Manufacturing | 2025 |
| Meyrick Estate Management Limited | Construction | 1969 |
| Minkie Limited | Manufacturing | 2004 |
| Mona Precast (Anglesey) Limited | Manufacturing | 1968 |
| Montoto Ltd | Professional & scientific | 2023 |
| Moss Computers Ltd | Other services | 2003 |
| Mynachdy Grass Converters Limited | Agriculture & fishing | 2014 |
| Nantanog Dairy Farm Limited | Extraterritorial | 1946 |