| Arcticles Oy | Administrative & support | 2023 |
| Arcticpipe & Weldservice Oy | Manufacturing | 2019 |
| Arcticusp Oy | Health & social care | 2025 |
| Arctine Oy | Administrative & support | 2024 |
| Arcturia Oy | Information & communication | 2007 |
| Arflix Oy | Arts & recreation | 2019 |
| AriJoyna Oy | Professional & scientific | 2012 |
| Arisen Oy | Professional & scientific | 2007 |
| Arkkitehdit Rantala & Kankaanpää Oy | Professional & scientific | 2021 |
| Arkkitehtisuunnittelu Hiilivirta Oy | Professional & scientific | 2000 |
| Arkkitehtitoimisto Rantakokko Oy | Professional & scientific | 2007 |
| Arkkitehtitoimisto SHY Oy | Professional & scientific | 2021 |
| Arkkitehtuuritoimisto Teuvo Kairesto Oy | Professional & scientific | 1991 |
| Arktikum-palvelu Oy | Arts & recreation | 1992 |
| Arktinen Halaus Oy | Professional & scientific | 2021 |
| Arktis-Rakennus Oy | Construction | 2017 |
| Arktiset Vedet Oy | Information & communication | 2018 |
| Arlabe Oy | Wholesale & retail | 2024 |
| Armidetta Oy | Hospitality | 2020 |
| Armstrong Henkilöstöpalvelut Rovaniemi Oy | Administrative & support | 2025 |
| Art Violeti Oy | Other services | 2013 |
| Artbaumeister Oy | Construction | 2000 |
| Arteca Ky | Wholesale & retail | 1991 |
| Artic-Freetec Oy | Construction | 1991 |
| Artica Agency Oy | Professional & scientific | 2022 |
| Artik Vision Oy | Professional & scientific | 2026 |
| Artorio Oy | Information & communication | 2017 |
| Asianajotoimisto Arctica Oy | Professional & scientific | 2020 |
| Asianajotoimisto Artus Ky | Professional & scientific | 2000 |
| Asianajotoimisto Esa Luomajoki Oy | Professional & scientific | 1997 |
| Asianajotoimisto Hiukka & Sandström Oy | Professional & scientific | 1994 |
| Asianajotoimisto Ilkka Ikäheimo Oy | Professional & scientific | 2010 |
| Asianajotoimisto Isomaa Ky | Professional & scientific | 2007 |
| Asianajotoimisto Juntura & Määttä Oy | Professional & scientific | 1975 |
| Asianajotoimisto Jurmu Oy | Professional & scientific | 2025 |
| Asianajotoimisto Karvo & Mella Oy | Professional & scientific | 1987 |
| Asianajotoimisto Laki-Forum Oy | Professional & scientific | 2023 |
| Asianajotoimisto Legista Oy | Professional & scientific | 2020 |
| Asianajotoimisto Lukkarila & Ahola Oy | Professional & scientific | 1975 |
| Asianajotoimisto Menna Oy | Professional & scientific | 2023 |
| Asianajotoimisto Miinala & Kaisanlahti Oy | Professional & scientific | 2013 |
| Asianajotoimisto Normia Oy | Professional & scientific | 2024 |
| Asianajotoimisto Oy Rovalex | Professional & scientific | 2002 |
| Asianajotoimisto Pulkamo Oy | Professional & scientific | 2013 |
| Asianajotoimisto Veikko Pyyny Ky | Professional & scientific | 1975 |
| Asianajotoimisto Ylisuvanto & Ahonen Oy | Professional & scientific | 2016 |
| Assaroi Oy | Hospitality | 2000 |
| Assertio Oy | Health & social care | 1989 |
| Atada Oy | Real estate | 2019 |
| Atelii Oy | Professional & scientific | 2025 |
| Ateljee Kuvastin Oy | Professional & scientific | 2013 |
| Atra Oy | Information & communication | 1988 |
| Atro Karttunen Ky | Transport & logistics | 2017 |
| Atsuuri Oy | Hospitality | 1991 |
| Audiovalo Oy | Wholesale & retail | 2015 |
| Audit Auer Oy | Professional & scientific | 2007 |
| Aulanpaljet Oy | Real estate | 1998 |
| Aurinkopuro Oy | Arts & recreation | 2016 |
| Auritus Oy | Hospitality | 1991 |
| Aurora Apartments & Taxi Oy | Transport & logistics | 2024 |
| Aurora Asunnot Oy LKV | Real estate | 2023 |
| Aurora Bei Ji Guang Oy | Administrative & support | 2016 |
| Aurora CMC Consulting Oy | Professional & scientific | 2021 |
| Aurora CMC Group Oy | Financial services | 2025 |
| Aurora Cartel Oy | Professional & scientific | 2025 |
| Aurora Energia Oy | Construction | 2026 |
| Aurora Enterprises Holding Oy | Professional & scientific | 2024 |
| Aurora Enterprises Oy | Wholesale & retail | 2017 |
| Aurora Flow Group Oy | Education | 2026 |
| Aurora Horizon Oy | Hospitality | 2025 |
| Aurora Lämpö Oy | Energy | 2005 |
| Aurora Magic Rentals Oy | Hospitality | 2024 |
| Aurora Powertrains Oy | Manufacturing | 2017 |
| Aurora Rovaniemi - The Official Northern Lights Center In Lapland Oy | Arts & recreation | 2025 |
| Auskul Oy | Real estate | 2020 |
| Auto Aho Oy | Wholesale & retail | 1980 |
| Auto ReSet Oy | Other services | 2021 |
| Auto-Niva Ky | Wholesale & retail | 1989 |
| Autocolorit Oy | Wholesale & retail | 2013 |
| Autohalli Haavikko Oy | Wholesale & retail | 1977 |
| Autohuolto Esa Rensujeff Ky | Other services | 1997 |
| Autohuolto Sysmäläinen Ky | Other services | 1986 |
| Autoidea Ky | Transport & logistics | 1981 |
| Autokorjaamo J. Koivuranta Oy | Other services | 2013 |
| Autokorjaamo P. Mourujärvi Oy | Other services | 2002 |
| Autokorjaamo VP Niemi Oy | Other services | 2013 |
| Autokorjaamo Vitikka Oy | Other services | 2024 |
| Automaalaus Mikkola Oy | Real estate | 1985 |
| Automyynti Heikki Marttila Ky | Transport & logistics | 1983 |
| Autopesu JR Oy | Other services | 2013 |
| Autoraita Jouko Hietala Ky | Other services | 1987 |
| Autorentlapland Oy | Administrative & support | 2005 |
| Autosähkö Huhtanen Oy | Other services | 1991 |
| Autosähköprofessori Oy | Other services | 2022 |
| Autotalo-Roi Ky | Real estate | 1983 |
| Autovi Systems Oy | Other services | 2000 |
| Avalio Oy | Administrative & support | 2010 |
| Avea Media Oy | Information & communication | 2017 |
| Avertum Oy | Wholesale & retail | 2011 |
| Avian Oy | Financial services | 2000 |