| Antti & Sari Kujala Ky | Wholesale & retail | 1994 |
| Antti Koskinen Holding Oy | Professional & scientific | 2023 |
| Antti Linnanmäki Oy | Transport & logistics | 2014 |
| Antwest Oy | Transport & logistics | 2008 |
| Apparatus kiinteistöt Oy | Real estate | 2003 |
| Aradito Oy | Information & communication | 2022 |
| Archtop Laminates Oy | Manufacturing | 2019 |
| Arcon Engineering Oy | Manufacturing | 2004 |
| Arctic Electric Vehicles Oy | Professional & scientific | 2014 |
| Arctic Mage Games Oy | Information & communication | 2021 |
| Arheila Oy | Arts & recreation | 2007 |
| Ari Pöytälaakso Oy | Transport & logistics | 2005 |
| Arjenilo Oy | Administrative & support | 2022 |
| Arkkikauppa Saarinen & Haapala Avoin yhtiö | Wholesale & retail | 2014 |
| Arkkitehti- ja insinööritoimisto Motiivi Oy | Professional & scientific | 2000 |
| Arkkitehtitoimisto Hirvilammi Oy | Professional & scientific | 2014 |
| Arkkitehtitoimisto Jouni Pitkäranta Oy | Professional & scientific | 2004 |
| Arkkitehtitoimisto Jyrki Jääskeläinen Oy | Professional & scientific | 1985 |
| Armas Palvelukiinteistöt Oy | Real estate | 2021 |
| Arosma Oy | Information & communication | 2024 |
| Arsalin Oy | Manufacturing | 1975 |
| Arttu Myllykangas Oy | Other services | 2024 |
| Artturi & Co avoin yhtiö | Other services | 2006 |
| Arvo Audit Oy | Professional & scientific | 2025 |
| Arvopaja Oy | Financial services | 2021 |
| Asaa Tekniikka Oy | Wholesale & retail | 2024 |
| Asennus Jo-Pa Oy | Construction | 2019 |
| Asennuspalvelu Riku Manninen Oy | Construction | 2021 |
| Asianajotoimisto Ahopelto Oy | Professional & scientific | 1989 |
| Asianajotoimisto Kattelus, Ruokola & Mukkala Oy | Professional & scientific | 2012 |
| Asianajotoimisto Malkamäki-Laurila Oy | Professional & scientific | 2024 |
| Asianajotoimisto Ristikangas & Koskinen Oy | Professional & scientific | 2023 |
| Asiantuntijapalvelu Vähämaa Oy | Professional & scientific | 2016 |
| Askeleittain Avopalvelut Oy | Health & social care | 2021 |
| Aslak Sales ky | Wholesale & retail | 2022 |
| Aspect Seinäjoki Oy | Wholesale & retail | 2008 |
| Aspen Lodges Oy | Real estate | 2018 |
| Aspäk Oy | Administrative & support | 2022 |
| Asuintupa Ky | Professional & scientific | 1995 |
| Ates auton käsinpesu Oy | Other services | 2022 |
| Atlasrate Oy | Professional & scientific | 1987 |
| Atmosnaut Oy | Financial services | 2020 |
| Atria Suomi Oy | Manufacturing | 2002 |
| Augment Group Oy | Administrative & support | 2015 |
| Augment Mobility Ab | Manufacturing | 2015 |
| Aukera-Invest Oy | Real estate | 2021 |
| Aulava oy | Hospitality | 2017 |
| Auroora Optiikka Oy | Wholesale & retail | 2024 |
| Aurora Advanced Energy Systems Oy | Professional & scientific | 2026 |
| AutoArta Oy | Wholesale & retail | 1987 |
| AutoPääkkönen Oy | Wholesale & retail | 2003 |
| Autohuolto Seitoy Oy | Other services | 2018 |
| Autohuolto Vesitorni Ky | Wholesale & retail | 1986 |
| Autokorjaamo Fin Mekanix Oy | Other services | 2023 |
| Automeca avoin yhtiö | Other services | 1994 |
| Automyynti Last Oy | Wholesale & retail | 2008 |
| Autosähkö Aimo Poola Ky | | 1985 |
| Avenext Oy | Administrative & support | 1981 |
| Avento Oy | Construction | 1985 |
| Avoin yhtiö Grilli-Pojat | Hospitality | 1972 |
| Avoin yhtiö K-Valinta Luttitalo | Wholesale & retail | 1984 |
| Avoin yhtiö Kuljetus-Lehtinen | Transport & logistics | 1985 |
| Avoin yhtiö Pääkkönen Petri ja Reijo | Construction | 1988 |
| Avoin yhtiö Ravintola Seinäjoen Mistral | Hospitality | 1992 |
| Avoin yhtiö Sweet'n FAB hair & make-up | Other services | 2022 |
| Avoin yhtiö Tallbacka & Tallbacka | Real estate | 1988 |
| Avoin yhtiö Tuula ja Heikki Wahlsten | Wholesale & retail | 1998 |
| Avot design Oy | Arts & recreation | 2012 |
| BEYA. Oy | Wholesale & retail | 2025 |
| Bisnar-Ingco OY | Hospitality | 2021 |
| BKK Betonilattiat Kari Koskinen Oy | Construction | 2015 |
| BOOBOO Oy | Wholesale & retail | 2025 |
| BRST Holding Oy | Financial services | 2025 |
| BSTR Luova Konttori Oy | Professional & scientific | 2008 |
| BTC Sijoitus Oy | Financial services | 2021 |
| Baran Ravintola Oy | Hospitality | 2022 |
| Barona Pohjanmaa Oy | Administrative & support | 2011 |
| Basaali Oy | Health & social care | 1990 |
| Battery Boys Ky | Wholesale & retail | 2011 |
| Beam Studio Oy | Manufacturing | 2023 |
| Beam-Net Oy | Manufacturing | 2013 |
| Beastmaker Oy | Information & communication | 2020 |
| Beingreallyawesome Oy | Other services | 2023 |
| Belin Group Oy | Financial services | 2021 |
| Bella Moda Oy Ltd | Wholesale & retail | 1991 |
| Benescan Oy | Health & social care | 1997 |
| BerBet Oy | Administrative & support | 2025 |
| Berekka Oy | Administrative & support | 2019 |
| Best one autojen käsinpesu Oy | Other services | 2022 |
| Best-In Oy | Manufacturing | 2002 |
| Betes Tuotanto Ky | Manufacturing | 1988 |
| Better Me For You Oy | Information & communication | 2025 |
| Biisoni Pohjanmaa Oy | Administrative & support | 2012 |
| BikerStyle Finland Oy Ltd | Construction | 2008 |
| Bilevempele OY | Wholesale & retail | 2025 |
| BioSor Finland Oy | Wholesale & retail | 2026 |
| Birdieman Oy | Wholesale & retail | 2006 |
| Black No. 1 Oy | Hospitality | 2025 |
| BlackSand Oy | Wholesale & retail | 2024 |
| Blankface Oy | Information & communication | 2021 |