| Asbest Team oy | Construction | 2020 |
| Asbestikartoitus Oy | Professional & scientific | 2007 |
| Ascom Oy | Manufacturing | 1996 |
| Asemanhoito TKS Oy | Real estate | 2017 |
| Asemanpuiston Grilli Koivisto & Tiainen | Hospitality | 1990 |
| Asennus Misso Oy | Administrative & support | 2013 |
| Asennus Teim Oy | Manufacturing | 2024 |
| Asennus imperiumi Oy | Construction | 2018 |
| Asfaltti Suoranta Oy | Professional & scientific | 2023 |
| Ashtanga Yoga Home Oy | Education | 2023 |
| Asian Choice Turku Oy | Wholesale & retail | 2025 |
| Asian food truck Oy | Hospitality | 2026 |
| Asianajotoimisto Aboa Oy | Professional & scientific | 2009 |
| Asianajotoimisto Ahtola Oy | Professional & scientific | 2011 |
| Asianajotoimisto Astrea Oy | Professional & scientific | 2001 |
| Asianajotoimisto Atrium Oy | Professional & scientific | 2012 |
| Asianajotoimisto Aura Oy | Professional & scientific | 1999 |
| Asianajotoimisto Avena Ager Oy | Professional & scientific | 2013 |
| Asianajotoimisto Brander & Manner Oy | Professional & scientific | 2001 |
| Asianajotoimisto Edelle Oy | Professional & scientific | 1995 |
| Asianajotoimisto Haaksiluoto & Kivimäki Oy | Professional & scientific | 2010 |
| Asianajotoimisto Hakanen Oy | Professional & scientific | 2008 |
| Asianajotoimisto Hanna Söderlund Oy | Professional & scientific | 2012 |
| Asianajotoimisto Heikki Jalas Oy | Professional & scientific | 1980 |
| Asianajotoimisto Heikki Sillanpää Oy | Professional & scientific | 2015 |
| Asianajotoimisto Heikki Virri Oy | Professional & scientific | 2000 |
| Asianajotoimisto Hinkkanen Oy | Professional & scientific | 2024 |
| Asianajotoimisto Hokkanen Huovinen & Rantanen Oy | Professional & scientific | 2014 |
| Asianajotoimisto J-M Kulmala Oy | Professional & scientific | 2007 |
| Asianajotoimisto Joni Brander Oy | Professional & scientific | 2025 |
| Asianajotoimisto Jorma Birling Ky | Professional & scientific | 1980 |
| Asianajotoimisto Juha Bang Oy | Professional & scientific | 2001 |
| Asianajotoimisto Kailiala Oy | Professional & scientific | 2000 |
| Asianajotoimisto Kivikoski & Haavisto Oy | Professional & scientific | 2015 |
| Asianajotoimisto Kroneld Oy | Professional & scientific | 1982 |
| Asianajotoimisto L Legal Oy | Professional & scientific | 2017 |
| Asianajotoimisto Laakso Laaksonen Vuorenvirta Oy | Professional & scientific | 2005 |
| Asianajotoimisto Laakso Toni Oy | Professional & scientific | 2007 |
| Asianajotoimisto Laineenkare Oy | Professional & scientific | 2006 |
| Asianajotoimisto Lakinainen Oy | Professional & scientific | 2013 |
| Asianajotoimisto Lasse Lahti Oy | Professional & scientific | 2004 |
| Asianajotoimisto Leena Toivonen Oy | Professional & scientific | 2022 |
| Asianajotoimisto Lindberg & Co Oy | Professional & scientific | 2024 |
| Asianajotoimisto Lindell Oy | Professional & scientific | 1995 |
| Asianajotoimisto Liuksila Ky | Professional & scientific | 1985 |
| Asianajotoimisto Palaja Oy | Professional & scientific | 2025 |
| Asianajotoimisto Perho Oy | Professional & scientific | 2023 |
| Asianajotoimisto Plathin Oy | Professional & scientific | 2002 |
| Asianajotoimisto Pontus Lindberg & Co Oy | Professional & scientific | 1993 |
| Asianajotoimisto Rintanen Oy | Professional & scientific | 2020 |
| Asianajotoimisto Roos & Co Oy | Professional & scientific | 2019 |
| Asianajotoimisto Saarnilehto Oy | Professional & scientific | 2024 |
| Asianajotoimisto Sonck Oy | Professional & scientific | 2022 |
| Asianajotoimisto Uronen Oy | Professional & scientific | 1997 |
| Asianajotoimisto Virkki Oy | Professional & scientific | 2018 |
| Asianajotoimisto Vuorio & Co Oy | Professional & scientific | 2016 |
| Asianajotoimisto Ylönen Oy | Professional & scientific | 2020 |
| Asiantuntijaosuuskunta Aboa Factum | Other services | 1996 |
| Asiantuntijaosuuskunta Ornanet | Professional & scientific | 1998 |
| Askartelu- ja taidetarvike Presento Oy | Wholesale & retail | 1989 |
| Askel Perhepalvelut Oy | Health & social care | 2026 |
| AskelAid Oy | Health & social care | 2019 |
| AskelFysio Oy | Health & social care | 2012 |
| Aslakin Lempi Oy | Arts & recreation | 2015 |
| Aspen Education Oy | Education | 2023 |
| Asplund & Kouki Oy | Financial services | 1987 |
| Asser Import Ky | Real estate | 1989 |
| Asset Partners Oy | Real estate | 2024 |
| Assiva Oy | Administrative & support | 2019 |
| Astonishing Badger Oy | Professional & scientific | 2022 |
| Astoria Kiinteistökehitys Oy | Real estate | 2020 |
| Astronave Oy | Professional & scientific | 2025 |
| Asuda Oy | Hospitality | 2023 |
| Asude Oy | Wholesale & retail | 2023 |
| Asumisoikeus Oy Rahikuja 3 Raisio | Real estate | 1991 |
| Asumisoikeus Oy Turun Hovimäenkatu 2 | Real estate | 2019 |
| Asunnonmyyntikeskus Turku Ky | Real estate | 2017 |
| Asunnot KMH Oy | Real estate | 2022 |
| Ataatos Oy | Professional & scientific | 1989 |
| Ateljee AGAMI Ky | Manufacturing | 2000 |
| Ateljee Linn Oy | Arts & recreation | 2021 |
| Ateria Puolikko Oy | Hospitality | 2014 |
| Ateriapalvelut NIL Oy | Hospitality | 2024 |
| Ateriapalvelut Yilmaz Oy | Real estate | 2005 |
| Atermek Oy | Professional & scientific | 1989 |
| Atfos Oy | Information & communication | 2014 |
| Athleron Oy | Wholesale & retail | 2017 |
| Atifjaved Avoin yhtiö | Administrative & support | 2020 |
| Atlas Group Oy | Manufacturing | 1990 |
| Atlas Import Oy | Real estate | 1987 |
| Atleti Oy | Arts & recreation | 2019 |
| Atmos Living Oy | Professional & scientific | 2022 |
| Atnum Oy | Professional & scientific | 2025 |
| Atoman (Finland) Semiconductor Technology Oy | Manufacturing | 2022 |
| Atomax Oy | Other services | 2023 |
| Atomic Music osk | Arts & recreation | 2018 |
| Atomic Yuzu Oy | Information & communication | 2023 |
| Attila Acquisitions Oy | Financial services | 2021 |
| AttoVerde Oy | Wholesale & retail | 2021 |
| Au-Holmberg Oy | Manufacturing | 2003 |