| Lännen Digital Antenni Oy | Construction | 2006 |
| Länsipahvi Oy | Manufacturing | 2009 |
| M-Kiinteistöpalvelu Oy | Administrative & support | 2007 |
| M. Nurmikko Oy | Transport & logistics | 2010 |
| M. Tuomi Oy | Construction | 1992 |
| MB Swingnet Oy | Other services | 2014 |
| MJT-Hitsauspalvelu Oy | Manufacturing | 2018 |
| MK-Taksi Oy | Transport & logistics | 2008 |
| MM-Koneurakointi Oy | Construction | 2004 |
| MP MAAILMA M & K Oy | Wholesale & retail | 2011 |
| MS-Avain Ky | Wholesale & retail | 2003 |
| MSI-eristys Oy | Manufacturing | 2023 |
| MT-Huoltoteam Oy | Administrative & support | 2008 |
| Maanrakennus Inkinen Oy | Construction | 2006 |
| Maanrakennus Ismo & Markus Tuominen Oy | Construction | 1998 |
| Maanrakennus Marela Oy | Construction | 2014 |
| Maanrakennus ja kuljetus Nylund Oy | Construction | 1996 |
| Maansiirto ja Kaivuu Lehto Oy | Mining & quarrying | 2022 |
| Mamikaara Oy | Manufacturing | 1990 |
| Marikointi Oy | Professional & scientific | 2024 |
| Markkinointi Niemiset Oy | Wholesale & retail | 1985 |
| Masku Consulting Oy | Professional & scientific | 2015 |
| Masku Gym Oy | Arts & recreation | 2011 |
| Maskun Auto Oy | Transport & logistics | 2006 |
| Maskun Axoni Ky | Health & social care | 2000 |
| Maskun Energia-Asennus Oy | Construction | 2026 |
| Maskun Fysioterapia Ky | Health & social care | 1985 |
| Maskun Isännöinti Oy | Professional & scientific | 2011 |
| Maskun Kalustetalo Oy | Wholesale & retail | 1983 |
| Maskun Kebab-Pizzeria Oy | Hospitality | 2007 |
| Maskun Kuntoutus Oy | Health & social care | 2023 |
| Maskun Leipomo-Konditoria Ky | Manufacturing | 1992 |
| Maskun Luontaispuoti Oy | Wholesale & retail | 2006 |
| Maskun Magneetit Oy | Wholesale & retail | 2024 |
| Maskun Markkinasähköistys Oy | Administrative & support | 2005 |
| Maskun Rakennushuolto Oy | Construction | 1985 |
| Maskun Talotekniikkatiimi Oy | Construction | 1999 |
| Maskun Terästuote Oy | Manufacturing | 1989 |
| Maskun TäysTuho Oy | Administrative & support | 2024 |
| Maskun Vesihuolto Oy | Water & waste | 2015 |
| Maskun kaivuutyö Oy | Construction | 2020 |
| Maskun palvelu Oy | Administrative & support | 2023 |
| Maskun-Rakennustyö Oy | Construction | 2010 |
| Mauri Kuustonen Oy | Professional & scientific | 1978 |
| Metallityöpaja Leppänen Ky | Real estate | 1979 |
| Mikton Metal Oy | Manufacturing | 2008 |
| Mimosan Kukka Masku Avoin yhtiö | Wholesale & retail | 2014 |
| Monitoimi-SaTa Ky | Administrative & support | 2007 |
| MtKp Ohjelmistot Oy | Information & communication | 2019 |
| MultiCut Oy | Manufacturing | 2008 |
| Myyntipalvelu Jalonen Oy | Real estate | 1989 |
| Mönni Palvelut Oy | Construction | 2024 |
| N Work Group Oy | Construction | 2026 |
| NCL Solutions Oy | Manufacturing | 2023 |
| NG-Centers Oy | Wholesale & retail | 2016 |
| NISKURI Ky | Wholesale & retail | 2015 |
| Nord Snowman OY Ltd | Manufacturing | 2021 |
| NRM Group Oy | Professional & scientific | 2023 |
| NVC air handling Oy | Wholesale & retail | 2022 |
| Naantalin Arvopaperi Oy | Financial services | 1986 |
| Naavasoft Oy | Information & communication | 2015 |
| Navimeth Oy | Financial services | 2024 |
| Netinductor Oy | Information & communication | 2001 |
| Netorek Aika Oy | Information & communication | 2009 |
| Netorek OY | Information & communication | 1998 |
| Noisette Oy | Professional & scientific | 2010 |
| Noja Group Oy | Manufacturing | 2015 |
| Nomu Kidswear Oy | Manufacturing | 2022 |
| Nordic Corporate Management Oy | Professional & scientific | 2005 |
| NorthLink Oy | Information & communication | 1995 |
| OKFix Oy | Manufacturing | 2020 |
| OY Protelum Ltd | Construction | 2006 |
| Olea Capital Management Oy | Financial services | 2019 |
| Oona Vartiainen Oy | Arts & recreation | 2015 |
| Osakeyhtiö Kuohu | Information & communication | 2008 |
| Oskun Rekkapesu & Huolto Oy | Other services | 1997 |
| Outogroup Carcare Oy | Other services | 2020 |
| Oy Alsu Ab | Real estate | 2009 |
| Oy Par-Kaivax Ab | Construction | 1996 |
| Oy R.G.S. Europe Ltd | Professional & scientific | 1994 |
| Oy Shippro Ltd | Professional & scientific | 1986 |
| PLM Solution Design Oy | Information & communication | 2002 |
| PMAC Oy | Professional & scientific | 2015 |
| PN Sähkö & Saneeraus Oy | Construction | 2011 |
| PN Trading Oy | Financial services | 2025 |
| PaaluPatruunat Oy | Construction | 2017 |
| Painokiila Rautanen Ky | Manufacturing | 1985 |
| Paistipoika Oy | Agriculture & fishing | 1973 |
| Pajutavi Oy | Wholesale & retail | 1978 |
| Palvelutalo Kesätuuli Oy | Health & social care | 2018 |
| Pasis Holding Oy | Administrative & support | 2022 |
| Paulina Salminen Surgery & Science Oy | Health & social care | 2025 |
| Pedro Investment Oy | Financial services | 2010 |
| Peittaus Nikander Oy | Manufacturing | 1997 |
| Perhekoti Ilola Oy | Health & social care | 2003 |
| Piemme Fitness Oy | Wholesale & retail | 1998 |
| Pienkoneurakointi A & J Leino | Construction | 2012 |
| Piha- ja mökkipalvelut TALK-KARI Oy | Administrative & support | 2013 |
| PikkuVipinä Oy | Wholesale & retail | 2026 |
| Porello Oy | Wholesale & retail | 2020 |