| Oy Lagerholm Invest Ab | Real estate | 1982 |
| Oy Lindström Hans Ab | Construction | 2006 |
| Oy Lomato Ab | Construction | 1979 |
| Oy Lovesto Ab | Other services | 1979 |
| Oy Loviisa Boat Service Ab | Manufacturing | 2015 |
| Oy Loviisan Almintalo | Real estate | 2023 |
| Oy Loviisan Smoltti Ab | Agriculture & fishing | 1986 |
| Oy Loviisan Terveyspalvelut Ab | Health & social care | 2019 |
| Oy Loviisanseudun Vesi - Lovisanejdens Vatten Ab | Water & waste | 1999 |
| Oy Lovisa Taxi Ab | Transport & logistics | 1974 |
| Oy Nispe Import Ab | Wholesale & retail | 1979 |
| Oy Oker-Blom Ab | Financial services | 2002 |
| Oy Petsamo Shipbroker Ab | Hospitality | 2010 |
| Oy Print Mill Ab | Manufacturing | 1985 |
| Oy Pro Österstjernan Ab | Manufacturing | 2002 |
| Oy Pyhtään Puutuote Ab | Construction | 1992 |
| Oy R. Nordström & Co Ab | Transport & logistics | 1971 |
| Oy Smart Guard Systems Ltd | Wholesale & retail | 1995 |
| Oy Stemon Ab | Wholesale & retail | 1992 |
| Oy Stockfors Ab | Agriculture & fishing | 1959 |
| Oy Syf-Line Ltd | Professional & scientific | 1995 |
| Oy Tarra-Tac Ab | Manufacturing | 1993 |
| Oy Te-Su Ab | Agriculture & fishing | 1962 |
| Oy Tikander-Metall Ab | Construction | 2000 |
| Oy Tilitupa Henry Friman Ab | Professional & scientific | 1989 |
| Oy Vakuutuspalvelu Bent Lindfors Försäkringstjänst Ab | Real estate | 1990 |
| Oy Windell & Riikonen Design Ltd | Professional & scientific | 1990 |
| P & P Painters Oy | Construction | 1995 |
| P.Tallberg Group Oy | Wholesale & retail | 2022 |
| Pekabe Oy | Construction | 2006 |
| Pelto-Kukka Sijoitus Oy | Financial services | 2008 |
| Pengermäkadun Huolto Oy Ab | Administrative & support | 2007 |
| Perfect White Oy | Professional & scientific | 2012 |
| Pernajan Sähkö Oy - Pernå El Ab | Construction | 1994 |
| Peter Högström Ky Kb | Construction | 1996 |
| Piia Väisänen Oy | Wholesale & retail | 2025 |
| Piiri Co Oy | Wholesale & retail | 2015 |
| Pikkune Oy | Professional & scientific | 2023 |
| Pittelil Productions Oy | Arts & recreation | 2022 |
| Pohjakuvat24 Oy | Professional & scientific | 2019 |
| Porvoonkatu 1 Loviisa Oy | Real estate | 2013 |
| Pripaks Kiinteistöt Oy | Real estate | 2008 |
| ProHouse Consulting Oy | Real estate | 2008 |
| Pu-Ra Oy | Construction | 2019 |
| Pyhänseita Oy | Real estate | 1999 |
| R. Nygårds Skog Ab | Agriculture & fishing | 2020 |
| RM Karlsson Oy | Wholesale & retail | 2012 |
| RMU Rakennusinvest Oy | Construction | 1991 |
| RT Vahtere Oy | Construction | 2008 |
| RTE-Consult Ky | Professional & scientific | 1990 |
| Radiologipalvelu Ritja Savolainen Oy | Health & social care | 2021 |
| Rakennusapu Puumalainen Oy | Construction | 2008 |
| Rakennuskonevuokraamo Kaino Mattila Oy | Administrative & support | 1976 |
| Rakennusliike PelNor Avoin yhtiö | Construction | 2010 |
| Rakennussuunnittelu Carling OY | Professional & scientific | 2014 |
| Rakennustoimisto Erkki Rahkonen Oy | Construction | 1993 |
| Rakennustyö Veljekset Huotari Oy | Construction | 1989 |
| RanoRa Ab | Real estate | 2016 |
| Rautahaukka Oy | Wholesale & retail | 2025 |
| Ravintola Ajuri Oy | Hospitality | 2025 |
| Ricado Oy | Wholesale & retail | 2017 |
| Riitta Puumalainen Oy | Administrative & support | 2011 |
| Risto Eklund Ky | Professional & scientific | 1994 |
| Rocc Oy/Ab | Real estate | 2021 |
| Rosenmarin AB OY | Other services | 2018 |
| Rospa Oy | Manufacturing | 1977 |
| Rosvall & Co Oy Ab | Wholesale & retail | 1963 |
| S-J Kiviranta Ky | Construction | 2005 |
| SISU Method Oy | Other services | 2023 |
| SJ Konsultointi Oy | Professional & scientific | 2019 |
| SL-Edustus Oy | Wholesale & retail | 2004 |
| SQS Consult Oy | Professional & scientific | 2026 |
| SafetyOn Oy | Professional & scientific | 2018 |
| Sakura Deli Oy Ab | Hospitality | 2020 |
| Sal-Ki Oy | Wholesale & retail | 2017 |
| Salon Kaj Kallio Oy Ab | Other services | 1978 |
| Salon Monika Grönqvist Oy | Other services | 1991 |
| Sarvlax vattenandelslag | Water & waste | 1990 |
| Satumaista elämää Oy | Health & social care | 2022 |
| Scan Traktor Oy Ab | Manufacturing | 2024 |
| Scanban-Kaiteet Ky | | 1973 |
| Screen-Top Lassas & Co Oy Ab | Real estate | 1983 |
| Seculton Finland Oy | Professional & scientific | 2018 |
| Sel-Tel Oy Ab | Construction | 1922 |
| Selenius team Oy | Construction | 2013 |
| Senorma Oy | Real estate | 2009 |
| Seppäläntien Lämpö Oy | Administrative & support | 1978 |
| Sidekick Working Oy | Construction | 2025 |
| Silver Zombie Oy | Arts & recreation | 2000 |
| Sinin Kakkukauppa Oy | Manufacturing | 2022 |
| Sipola Invest Oy | Wholesale & retail | 2021 |
| Sistola Oy | Wholesale & retail | 1949 |
| Sisura Oy | Construction | 2018 |
| Skogsreviret Nyved Ab | Professional & scientific | 1993 |
| Sourcing Net Oy | Professional & scientific | 2008 |
| Specta International Oy | Wholesale & retail | 2025 |
| Starmarine Ky | Wholesale & retail | 1987 |
| Stig Rosenqvist-Auto Ky/Kb | Wholesale & retail | 1992 |
| Storymaster Oy Ab | Professional & scientific | 2002 |
| Studio Soul Oy | Other services | 2025 |