| Koski Living Oy | Real estate | 2025 |
| Kucco Oy | Wholesale & retail | 2020 |
| Kuljetus Huusko Oy | Transport & logistics | 2008 |
| Kuljetus Jocceri Ky | Transport & logistics | 2022 |
| Kuljetus Jyri Seikkala Oy | Transport & logistics | 2017 |
| Kuljetus Kokkoniemi Oy | Transport & logistics | 2020 |
| Kuljetus M & S Virkkula Oy | Transport & logistics | 2024 |
| Kuljetus- ja lokapalvelu Kyllönen Oy | Water & waste | 2022 |
| Kuljetusliike Eskola Oy | Transport & logistics | 1991 |
| Kuljetusliike Lallukka Oy | Transport & logistics | 2016 |
| Kuontiranta Oy | Hospitality | 2021 |
| Kärki Works Oy | Construction | 2025 |
| LTS Holdings OY | Financial services | 2016 |
| LVI ja Sähkö Heikkinen Oulu Oy | Construction | 2022 |
| Lahti Products Oy | Wholesale & retail | 2021 |
| LateKoo Oy | Financial services | 2026 |
| Levelco Oy | Real estate | 2018 |
| Liekokylän Vesiosuuskunta | Water & waste | 1992 |
| Liikuntakeskus Come on Fit Club Oy | Arts & recreation | 2016 |
| Logser oy | Other services | 2026 |
| Loistavin Oy | Construction | 1993 |
| Lukadus Oy | Health & social care | 2008 |
| M&T Productions Ky | Professional & scientific | 2017 |
| M-team Oy | Information & communication | 1993 |
| MHB Invest Oy | Financial services | 2025 |
| MINET Urakointi Oy | Transport & logistics | 2021 |
| MKY Palvelut Oy | Construction | 2007 |
| MRA EcoPath Oy | Information & communication | 2024 |
| MU Holding Oy | Professional & scientific | 2023 |
| Maanrakennus Han-Kia Oy | Construction | 2009 |
| Maanrakennus Neuvonen Oy | Construction | 2007 |
| Maanrakennus Paso Oy | Construction | 2026 |
| Maanrakennus Tuohimaa Ky | Real estate | 2010 |
| Maansiirto ja Kuljetus Leppälä avoin yhtiö | Transport & logistics | 1995 |
| Maarakennus Eskola Oy | Transport & logistics | 1994 |
| Maatila Arja ja Pertti Kuisma | Agriculture & fishing | 1993 |
| Masan huolto & metallipalvelu Oy | Manufacturing | 2024 |
| MedSara-Sofia Oy | Health & social care | 2023 |
| Merelco Oy | Professional & scientific | 2006 |
| Metonmäki Oy | Professional & scientific | 2020 |
| Miniahomes Oy | Manufacturing | 2021 |
| Moto-Salo Consulting Oy | Professional & scientific | 2023 |
| Mototyö J Tuohimaa Ky | Agriculture & fishing | 2019 |
| N. Tauriaisen korjaamo Ky | | 1983 |
| Natpel Oy | Wholesale & retail | 1996 |
| Ni-Ro Oy | Arts & recreation | 2009 |
| Niekkarin Tennis Oy | Arts & recreation | 1990 |
| Nopsat Paketit Oy | Transport & logistics | 1991 |
| Norcla Oy | Manufacturing | 2022 |
| Nordic Fence Oy | Wholesale & retail | 2025 |
| OKL Finland Oy | Financial services | 2022 |
| Omg Kapu OY | Administrative & support | 2011 |
| Ohjelmistohuolto Vaarala Oy | Information & communication | 2018 |
| Ola Rakennus Oy | Construction | 2025 |
| Online Trade Finland Oy | Wholesale & retail | 2014 |
| Osmo Polojärvi Oy | Construction | 2007 |
| Oulu Custom Bike Oy | Other services | 2025 |
| Oulun Ekolämpö Oy | Construction | 2008 |
| Oulun Kone ja Terä Oy | Wholesale & retail | 1992 |
| Oulun Konemyynti Oy | Wholesale & retail | 2011 |
| Oulun Lattiat Oy | Construction | 2016 |
| Oulun Rakennus ja Saneeraus Oy | Construction | 2012 |
| Oulun Rehtiauto Ky | Wholesale & retail | 2008 |
| Oulun Sähköasennus Oy | Construction | 2012 |
| Oulun lattiapinta Oy | Construction | 2026 |
| Oulunseudun Eläinkeskus Oy | Other services | 2005 |
| Oy Finland Tower Investments Ab | Financial services | 1998 |
| Oy KiimAA | Professional & scientific | 2025 |
| Oy Poltronic Ab | Professional & scientific | 2006 |
| Patlog OY | Transport & logistics | 2024 |
| Palbassador Oy | Information & communication | 2019 |
| Pehaco Oy | Construction | 2021 |
| PeizaLa Invest Oy | Financial services | 2025 |
| Pernu Invest Group Oy | Real estate | 2006 |
| Perukka Oy | Hospitality | 2007 |
| Pineslope Oy | Wholesale & retail | 2024 |
| Planstation Oy | Professional & scientific | 2026 |
| Pohjois-Suomen Pelletti Ky | Manufacturing | 2003 |
| Pohjoisen Metsälannoituspalvelu Oy | Agriculture & fishing | 2019 |
| Polkukarkelo Oy | Arts & recreation | 2024 |
| Pororajalla Ky | Wholesale & retail | 2023 |
| Presentia Oy | Health & social care | 2023 |
| Pub humina Oy | Hospitality | 2026 |
| Pumppaus Paron Oy | Construction | 2023 |
| Puutavaraliike A. Tuohimaa ky | Wholesale & retail | 1989 |
| Puutyö Tuohimaa & Ronkainen | Manufacturing | 2018 |
| Päiväkoti Mansikkamaa Oy | Education | 2000 |
| RS Reserva Oy | Financial services | 2022 |
| Rs-Install OY | Construction | 2004 |
| Radiologipalvelu Laukkanen Oy | Health & social care | 2020 |
| Rakennus HH Avoin Yhtiö | Construction | 2005 |
| Rakennus ja AsennusPalvelu Ahola Ky | Construction | 2012 |
| Rakennus ja Saneeraus Ylipahkala & Määttä Oy | Construction | 2010 |
| Rakennusliike R & S-L Hänninen | Construction | 1991 |
| Rasiaklubi Oy | Other services | 2025 |
| Ravintola Arkan oy | Hospitality | 2025 |
| Ravintola Doski avoin yhtiö | Hospitality | 2022 |
| Ravintola Maron Ky | Hospitality | 2014 |
| Rengas-Arppa Oy | Wholesale & retail | 2022 |
| RiTim Consulting Oy | Information & communication | 2022 |