| Mariehamns Taxi Ab | Transport & logistics | 1996 |
| Mariehamns Taxi Service Ab | Transport & logistics | 2013 |
| Mariehamns Tidningstjänst Ab | Wholesale & retail | 1984 |
| Mariehamns Tryckeri Ab | Manufacturing | 1938 |
| Mariehamns hamn Ab | Transport & logistics | 2014 |
| Mariehav Ab | Real estate | 2025 |
| Mariehem Ab | Real estate | 2018 |
| Mariehus Ab | Real estate | 2020 |
| Mariepark Ab | Arts & recreation | 1995 |
| Mariepark Retail Ab | Wholesale & retail | 2016 |
| Marin & Industri-Teknik MK Ab | Professional & scientific | 1984 |
| Marin Teknik OTL Ab | Administrative & support | 1996 |
| Marin och motorshoppen Ab | Wholesale & retail | 2023 |
| Marineparts Holding Ab | Financial services | 2021 |
| Marinlagret Möckelö Ab | Real estate | 2021 |
| Mariterra Ab | Financial services | 1988 |
| Marjolar Ab | Financial services | 2005 |
| Martins Resor Ab | Administrative & support | 2008 |
| Maskin & Produkt, Nils Mattsson Kb | Wholesale & retail | 1978 |
| Maskin-Import, Holger Sjöström Ab | Wholesale & retail | 1982 |
| Mastberget Ab | Financial services | 1989 |
| Matgrossisten Åland Ab | Wholesale & retail | 2012 |
| Matkreatören i Mariehamn Ab | Hospitality | 2023 |
| Matligan Ab | Hospitality | 2022 |
| Mattsson & Landström | Financial services | 2013 |
| Mattsson Holding Ab | Financial services | 2018 |
| Medical Serve Ab | Health & social care | 2020 |
| Medimar Scandinavia Ab | Health & social care | 2007 |
| Megasize Reklam Ab | Professional & scientific | 2005 |
| Melpal Trading Ab | Real estate | 2011 |
| Memento Psykologi Ab | Health & social care | 2025 |
| Mephoto Ab | Professional & scientific | 2024 |
| Merrem Ab | Professional & scientific | 2019 |
| Metal Store Finland Oy | Wholesale & retail | 2014 |
| Mickos's Ritateljé & Arkitektstudio Ab | Professional & scientific | 1995 |
| Mike Alpha Ab | Financial services | 2007 |
| Mike Bravo Ab | Financial services | 2007 |
| Mike Charlie Ab | Financial services | 2007 |
| Mike Whiskey Ab | Financial services | 2007 |
| Mildreds kompani öppet bolag | Education | 2010 |
| Milestone Group Ab | Education | 2009 |
| Milli & Molly Ab | Real estate | 2019 |
| Mineral Stenhuggeri Höckböle Ab | Mining & quarrying | 2025 |
| Mira Food Ab | Hospitality | 2018 |
| Mituna IT-service Oy | Information & communication | 2024 |
| Moderamen Ab | Professional & scientific | 2012 |
| Moma Ab | Health & social care | 1995 |
| Moneymaker Invest & Consulting Kb | Financial services | 1999 |
| Motax Ab | Other services | 2020 |
| Mson Invest Ab | Professional & scientific | 2021 |
| Multitronic Åland Ab | Wholesale & retail | 2015 |
| MusseÅgänget öppet bolag | Education | 2023 |
| My Ak Ab | Administrative & support | 2013 |
| My Company Ab | Education | 2008 |
| Mäklarhuset Åland Ab | Real estate | 2013 |
| Mätkonsult Åland Ab | Professional & scientific | 2017 |
| Målar-Fix Ab | Construction | 2020 |
| Möbelhörnan, V. Nikula & Co. | Wholesale & retail | 1944 |
| Mörkös vattenandelslag | Water & waste | 2011 |
| NCC Åland Ab | Manufacturing | 2022 |
| NE invest Oy | Wholesale & retail | 2023 |
| NH Konsult Ab | Professional & scientific | 2021 |
| Nordipoint AB | Information & communication | 2009 |
| NTG Alandia Ab | Wholesale & retail | 2007 |
| Natura Consult Ab | Financial services | 1987 |
| Navito Ab | Professional & scientific | 2022 |
| Ndlovu Ab | Financial services | 1989 |
| Nems Ab | Professional & scientific | 1987 |
| NeverforgetTM Ab | Information & communication | 2025 |
| NiWi Ab | Real estate | 2006 |
| Nikapack Ab | Wholesale & retail | 2014 |
| Nikulas Svets & Smide öppet bolag | Manufacturing | 2005 |
| No 1, Lindström & Co Ab | Administrative & support | 1988 |
| Nobel Fastigheter Ab | Real estate | 1989 |
| Nonna Rina AB | Hospitality | 2016 |
| Nora-hus Ab | Construction | 2007 |
| Nord Ren Ab | Administrative & support | 2026 |
| Nord-Marin Småbåtsvarvet Ab | Wholesale & retail | 1991 |
| Nordberg Consulting Ab Oy | Information & communication | 2026 |
| Nordeka AB | Wholesale & retail | 2025 |
| Nordic Expedition Sailing Society Oy | Transport & logistics | 2024 |
| Nordic Mystery Shopping Suomi Oy Ab | Education | 2017 |
| Nordisk Spisimport ab | Wholesale & retail | 2021 |
| Nordiska Fastigheter Ab | Real estate | 2024 |
| Nordiskt Byggmaterial Ab | Professional & scientific | 1989 |
| Nordiskt Material Ab | Professional & scientific | 2011 |
| Nordmec Ab | Manufacturing | 2022 |
| Nordplan Ab | Professional & scientific | 2025 |
| Nordpolen tjänster Ab | Professional & scientific | 2022 |
| Nordum Invest Ab | Financial services | 2026 |
| Normapak Ab | Administrative & support | 2006 |
| Norra Ålands Avloppsvatten Ab | Water & waste | 2003 |
| Norrböle Business Park Ab | Real estate | 2024 |
| Norrfjärden Ab | Financial services | 1990 |
| Norrhavets Sjötransport Ab | Transport & logistics | 2024 |
| Norrnäs fastigheter Ab | Real estate | 2025 |
| Norrsken Fastigheter Ab | Financial services | 2011 |
| Nova Buss Ab | Transport & logistics | 2025 |
| Nova Perch Ab | Agriculture & fishing | 1997 |
| Novamare Partners Ab | Professional & scientific | 2019 |