| 1586 Marika Paalanen Oy | Wholesale & retail | 2017 |
| 1700 Anne Elo Oy | Wholesale & retail | 2019 |
| A la Makii Foods Oy | Hospitality | 2024 |
| AK-Asennus Antti Koskimäki Oy | Wholesale & retail | 1996 |
| AS Convert Oy | Wholesale & retail | 2021 |
| AVH Satalinna Oy | Real estate | 2015 |
| Ansi-Tuote om. Sirkka ja Ilkka Huhtala | Manufacturing | 1975 |
| Antellax Oy | Wholesale & retail | 1993 |
| Antero&Antero Oy | Wholesale & retail | 2022 |
| Axe-Tech Oy | Manufacturing | 2011 |
| BestVillas Oy | Hospitality | 2021 |
| Bikestoppi Oy | Other services | 2014 |
| Boliden Harjavalta Oy | Manufacturing | 2000 |
| Casinhas Oy | Real estate | 2024 |
| ChangeForce Oy | Professional & scientific | 2026 |
| Dermis Oy | Health & social care | 1988 |
| Devil's Ridge Oy | Wholesale & retail | 2024 |
| Drift Madness Oy | Arts & recreation | 2021 |
| EJH rock oy | Financial services | 2025 |
| EK-Kyyti Oy | Transport & logistics | 2023 |
| Eleva Oy | Professional & scientific | 2023 |
| Elämyspalvelut Härkälä Oy | Arts & recreation | 2016 |
| Erämieli Oy | Arts & recreation | 2025 |
| Euran Timanttisahaus Ky | Construction | 1989 |
| Eurape Oy | Construction | 2001 |
| Eurofinnmet European Finnish Metals Ltd Oy | Water & waste | 1995 |
| Fistekno Oy | Professional & scientific | 1994 |
| Fixtori Oy | Wholesale & retail | 2020 |
| Fortum Battery Recycling Oy | Manufacturing | 2005 |
| FysioTutka Oy | Health & social care | 1981 |
| Gala Kebab Pizzeria Ky | Hospitality | 2004 |
| HARJAVALLAN AUTO JA METALLI Ky | Wholesale & retail | 2002 |
| Hedec OY | Construction | 2020 |
| HEM.co Oy | Wholesale & retail | 2024 |
| HJ-Konsultointi Oy | Professional & scientific | 2018 |
| Hakuva Oy | Real estate | 2007 |
| HallWay Oy | Administrative & support | 2022 |
| Harjavallan A&T Autopalvelu Oy | Other services | 1993 |
| Harjavallan Aero Oy | Real estate | 1992 |
| Harjavallan Hallit II Oy | Administrative & support | 1996 |
| Harjavallan Hiekka ja Sora Oy | Wholesale & retail | 2003 |
| Harjavallan JT-Kiinteistö Oy | Real estate | 1989 |
| Harjavallan Jäähalli Oy | Real estate | 1999 |
| Harjavallan Kaukolämpö Oy | Energy | 2005 |
| Harjavallan Kiinteistöpalvelu Oy | Manufacturing | 2013 |
| Harjavallan Kirjakauppa ky | Wholesale & retail | 1983 |
| Harjavallan Kotikulma Oy | Real estate | 2016 |
| Harjavallan Kuvakeskus Ky | Wholesale & retail | 1984 |
| Harjavallan LVI-Piste Oy | Construction | 2022 |
| Harjavallan Leipomo Ky, Ari Kallas | Administrative & support | 1968 |
| Harjavallan Metallirakenne Oy | Manufacturing | 1992 |
| Harjavallan Pizzamestarit Oy | Hospitality | 1992 |
| Harjavallan Saha Oy | Manufacturing | 1916 |
| Harjavallan Sairaankuljetus Oy | Health & social care | 1983 |
| Harjavallan Taksipalvelu Oy | Transport & logistics | 2015 |
| Harjavallan Trade JMR Oy | Manufacturing | 1993 |
| Harjavalta Oy | Financial services | 1922 |
| Harjavalta Transport Oy | Transport & logistics | 2014 |
| Harjavalta Ventures Oy | Financial services | 2023 |
| Havesan Oy | Agriculture & fishing | 2006 |
| HiMePa Oy | Manufacturing | 2025 |
| Hiittenharjun TeeBee Avoin yhtiö | Hospitality | 2006 |
| Hirsiveisto Kiuru Oy | Construction | 2017 |
| Holmiworks Oy | Construction | 2022 |
| Hopeasyli Oy | Health & social care | 2025 |
| Iett OY | Extraterritorial | 2021 |
| In-West&Realestate Oy | Other services | 2023 |
| Insinööritoimisto Koikkalainen Oy | Professional & scientific | 2019 |
| Insteam Consulting Oy | Professional & scientific | 2012 |
| Isännöintikeskus Sydän-Satakunta Oy | Real estate | 2025 |
| Itsmyid oy | Information & communication | 2023 |
| J ja J Mikola Oy | Real estate | 2014 |
| J.Ovaskainen Oy | Construction | 2013 |
| Jj-Pipe OY | Construction | 2016 |
| Jk-Pipe OY | Construction | 2015 |
| JKS Rakentajat Oy | Construction | 2015 |
| JL welding OY | Other services | 2026 |
| Jajopa Oy | Professional & scientific | 1987 |
| JerJoa Kiinteistöt Oy | Real estate | 2024 |
| JerJoa Service Oy | Other services | 2020 |
| JerJoa Yhtiöt Oy | Financial services | 2024 |
| Jokilaakson Peukaloiset Ky | Manufacturing | 1992 |
| Jokilaakson Tili- ja Yrityspalvelu Oy | Professional & scientific | 2013 |
| Jokilaakson taksit oy | Transport & logistics | 2013 |
| Jouhan Oy | Administrative & support | 2005 |
| JuPiTi Oy | Real estate | 2007 |
| KEV Urakointi Oy | Administrative & support | 2026 |
| Kaasanmäki Oy | Construction | 2021 |
| Kalaliike ja Ruokala Tulema Avoin yhtiö | Hospitality | 1993 |
| Kallen Market Ky | Wholesale & retail | 1987 |
| Kartok Ky | Other services | 1991 |
| Karvian Auto Oy | Wholesale & retail | 1988 |
| Karweld Oy | Manufacturing | 2021 |
| Kauneushoitola Ritva Mäkinen Ky | Other services | 2007 |
| Kause Oy | Manufacturing | 1987 |
| Kiinteistö Oy Aittoperän Kokkoniemi | Real estate | 1991 |
| Kiinteistö Oy Hamera | Real estate | 1994 |
| Kiinteistö Oy Harjavallan Hallit | Real estate | 1999 |
| Kiinteistö Oy Harjavallan Pienkatu 5 | Real estate | 1990 |
| Kiinteistö Oy Harjavallan Revonkulma | Real estate | 1994 |