| Lewis Construction & Plant Hire Ltd | Construction | 2014 |
| Life Full Colour Art Fusion CIC | Arts & recreation | 2021 |
| Life Full Colour Limited | Construction | 2019 |
| Life in Full Colour LLP | | 2019 |
| Lifting and Safety Limited | Manufacturing | 2015 |
| Lingo - Lowri Gwyn CYF | Administrative & support | 2011 |
| Lizzy's Limited | Hospitality | 2023 |
| LL Landscaping Ltd | Administrative & support | 2023 |
| Llama Properties Limited | Real estate | 2024 |
| Llanberis Asian Curry Limited | Hospitality | 2022 |
| Llanberis Leisure Limited | Hospitality | 2002 |
| Llanberis Resoles Ltd | Other services | 2021 |
| Llanrug Monumental Masons Limited | Other services | 2014 |
| Llech Y DWR Ltd | Hospitality | 2020 |
| Llechi Slate Evolution CYF | Mining & quarrying | 2021 |
| Llety Llanfair CYF | Hospitality | 2022 |
| Lleucu Roberts CYF | Information & communication | 2018 |
| Llinos WYN Jones CYF. | Households | 2020 |
| Lloyd Evans & Hughes CYF | Professional & scientific | 2020 |
| Llwyd Properties Ltd | Construction | 2023 |
| Lock UP Caravan Storage Ltd | Real estate | 2015 |
| Lock UP Self Storage Ltd | Transport & logistics | 2012 |
| Lockwood Consulting Ltd | Professional & scientific | 2021 |
| Lodge Holidays Limited | Hospitality | 2014 |
| Loffhagen Consultants Ltd | Professional & scientific | 2025 |
| Lone Tree Cafe Limited | Hospitality | 2020 |
| Loutre Consultancy Limited | Professional & scientific | 2025 |
| Lucidity Consulting Limited | Information & communication | 2010 |
| Lucky Dragon Fish Limited | Hospitality | 2024 |
| Luminos Memories Ltd | Wholesale & retail | 2024 |
| Lynwood Building Contractors Limited | Construction | 2005 |
| M & G Sound Holdings Ltd | Administrative & support | 2026 |
| M Jones Scaffolding Ltd | Construction | 2019 |
| M Williams Electrical Limited | Construction | 2014 |
| M&S Concrete Imprinting Ltd | Construction | 2016 |
| Mabinogi Deli Ltd | Hospitality | 2024 |
| Macwel Ltd | Other services | 2021 |
| Madontime Limited | Professional & scientific | 2014 |
| Maes Elwy Hydro Limited | Energy | 2013 |
| Mantell Gwynedd CYF. | Other services | 1997 |
| Marchnata Aqua Marketing Limited | Administrative & support | 2007 |
| Marvin Pritchard Martial Arts Ltd | Education | 2014 |
| Mashuda Limited | Hospitality | 2019 |
| Mathcyf CYF | Professional & scientific | 2016 |
| Matrix 10 Limited | Information & communication | 2001 |
| Maxelin Ltd | Administrative & support | 2015 |
| Mcfay Developments Limited | Construction | 2019 |
| Medacc Ltd | Professional & scientific | 2010 |
| Medi (Caernarfon) CYF | Hospitality | 2003 |
| Medrwn CYF | Manufacturing | 2012 |
| Melltd Ltd | Construction | 2026 |
| Menai Blinds Ltd | Manufacturing | 2008 |
| Menai Powder Coating Ltd | Manufacturing | 2009 |
| Menai Tractors Ltd | Manufacturing | 2007 |
| Menter Cymunedol Bethel CBC | Wholesale & retail | 2024 |
| Menter Fachwen | Health & social care | 1988 |
| Menter Iaith Gwynedd CYF | Education | 2023 |
| Mettlex Ltd | Wholesale & retail | 2025 |
| Mewn Geiriau CYF | Information & communication | 2023 |
| Miss Bela Ltd | Professional & scientific | 2013 |
| Moba (Museum of Bitcoin Art) Limited | Wholesale & retail | 2023 |
| Modurdy Dolydd Garage CYF | Wholesale & retail | 2016 |
| Moduron LMC Motors Ltd | Wholesale & retail | 2024 |
| Moduron Menai CYF | Wholesale & retail | 2005 |
| Moduron Worth CYF | Wholesale & retail | 2019 |
| Montgomery Maintenance Ltd | Real estate | 2025 |
| MOR Perfumery Limited | Wholesale & retail | 2025 |
| Morfarch Ltd | Hospitality | 2023 |
| Morgan European Logistics Limited | Transport & logistics | 2017 |
| Morgeisi Menai Mortgages Limited | Financial services | 2004 |
| Morris Build for Life Limited | Construction | 2014 |
| Mountainxperience Ltd | Education | 2024 |
| Moxgen Ltd | Construction | 2012 |
| MR Chwipi Ltd | Hospitality | 2026 |
| Mylo Capital Limited | Professional & scientific | 2017 |
| Mzore 2025 Ltd | Hospitality | 2025 |
| NA NI Media CYF | Information & communication | 2014 |
| Nalssauna Ltd | Arts & recreation | 2025 |
| Nant HIR Hydro Scheme Limited | Administrative & support | 2016 |
| Nant Technical Services Ltd | Energy | 2021 |
| Nant Tree Services Limited | Administrative & support | 2016 |
| Nebo Woodland Company Ltd | Agriculture & fishing | 2022 |
| Neuadd Y Farchnad Limited | Hospitality | 2024 |
| Next Adventure Ltd | Information & communication | 2019 |
| NIA Parry Cyfyngedig | Information & communication | 2009 |
| Nick Wood Music UK Ltd | Information & communication | 2024 |
| Nippers Nook Holidays Ltd | Hospitality | 2022 |
| Nook Snowdonia Ltd | Hospitality | 2015 |
| North Wales Canine Breeding Services Ltd | Agriculture & fishing | 2021 |
| North Wales First AID Ltd | Professional & scientific | 2025 |
| North Wales Flight Academy Ltd | Transport & logistics | 2014 |
| North Wales Liquid Screed Ltd | Construction | 2020 |
| North Wales Rivers Trust Ltd | Arts & recreation | 2007 |
| North-West Steel Services Ltd | Manufacturing | 2020 |
| Northwalesaudio Ltd | Administrative & support | 2025 |
| Nrgallacher Renewables Limited | Professional & scientific | 2026 |
| Nuget AUR / Golden Nugget CYF | Hospitality | 2025 |
| O'Brien Offshore Ltd | Construction | 2025 |
| Oberon Plumbing and Electrics Limited | Administrative & support | 2008 |
| OGC Creative Group Ltd | Information & communication | 2025 |