| Castor Consulting Oy | Kajaani | 2025 |
| Castor Real Estate Oy | Espoo | 2016 |
| CastorCon Finland Oy | Espoo | 2009 |
| Casual Homes Oy | Espoo | 2015 |
| CatMarina Oy | Hollola | 1989 |
| Cataja Oy | Evitskog | 2012 |
| Catamaran Real Estate Oy | Helsinki | 2021 |
| Catania Group Oy | Lahti | 2007 |
| Catarina investments oy | Hyvinkää | 2025 |
| Catcon Oy | Nurmo | 2017 |
| Cate-Trust Oy | Järvenpää | 1994 |
| Cateco Oy | Hyvinkää | 2017 |
| Catella Asset Management Oy | Helsinki | 2009 |
| Catella Property Oy | Helsinki | 2009 |
| Catena Holding Aviatie 2 Oy | Helsinki | 2020 |
| Catena Holding Ilvesvuorenkatu 8 Oy | Helsinki | 2021 |
| Catena Holding Moreenikatu 5 Oy | Helsinki | 2020 |
| Catena Holding Polarpakintie 4 Oy | Helsinki | 2017 |
| Catena Åbyntien Kiinteistöt Oy | Helsinki | 2019 |
| Catnip Oy | Helsinki | 2015 |
| Catpe Invest Oy | Helsinki | 2020 |
| Catrame Oy | Oulu | 2020 |
| Cavalier Venues Oy | Helsinki | 2026 |
| Cave Ventures Oy Ab | Helsinki | 2025 |
| Caverna Oy | Helsinki | 2021 |
| Cavitas Oy | Espoo | 1999 |
| Cee-Kiinteistöt Oy | Hamina | 2013 |
| Ceino Kiinteistöhallinta Oy | Espoo | 2020 |
| Celco Kiinteistöt Oy | Nurmijärvi | 2013 |
| Cellit Invest Ltd Oy | Espoo | 2004 |
| Cellit Oy Ab | Espoo | 1999 |
| Celocia Oy | Timola | 2026 |
| Cembe Kiinteistöt 2 Oy | Osoite Tuntematon | 2021 |
| Cembe Kiinteistöt Oy | Osoite Tuntematon | 2020 |
| Cemec Consulting Engineers Oy Ltd | Lappeenranta | 2006 |
| Centa Oy | Helsinki | 2026 |
| Cental Oy | Tampere | 2000 |
| Centaurus Finland Ky | Espoo | 2020 |
| Centena Invest Oy | Varkaus | 1993 |
| Central Office Finland Oy | Tampere | 2011 |
| Centre-Kiinteistöt Oy | Lappeenranta | 2014 |
| Centrum Isännöinti Oy | Turku | 2022 |
| Centrum i Mariehamn Ab | Mariehamn | 2016 |
| Centteri Oy | Lautiosaari | 2019 |
| Centurion Realty Oy | Helsinki | 2022 |
| Cepidus Oy | Vesilahti | 1996 |
| Cerenus Oy | Lempäälä | 2020 |
| Cerita öppet bolag | Böle | 1977 |
| Cernuus Oy | Köyliö | 2019 |
| Ceronen Oy | Valtimo | 2025 |
| Cerrado Capital Oy | Espoo | 2024 |
| Certus PropCo Oy | Helsinki | 2025 |
| Certus Properties HoldCo II Oy | Helsinki | 2025 |
| Certus Properties HoldCo Oy | Helsinki | 2024 |
| Cerutum Oy | Laitila | 2019 |
| Cervus Capital Holding II Oy | Helsinki | 2024 |
| Cesam Oy | Kauniainen | 2010 |
| Cetula Invest Oy | Ylivieska | 2020 |
| ChaKa Oy | Hyvinkää | 2000 |
| Chainsaw Capital Oy | Helsinki | 2021 |
| Chalet Rentals Finland Oy | Jyväskylä | 2024 |
| Chaps Invest Oy | Tenhola | 2020 |
| Charlottenberg Oy | Lapinkylä | 2014 |
| Charter-kodit Oy | Espoo | 2019 |
| Chase Capital Oy | Vanhalinna | 2026 |
| Cheng Wang Oy | Espoo | 2012 |
| ChicBO Oy | Helsinki | 2021 |
| China Harbour Engineering Company Limited, Suomen sivuliike | Helsinki | 2025 |
| China Palace Oy | Helsinki | 2017 |
| Chippendale-kiinteistöt Oy | Sastamala | 1951 |
| Chris-Craft Oy | Helsinki | 2020 |
| Chrispe-Invest Oy Ab | Tammisaari | 2000 |
| Christa Stirkkinen Investments Oy | Lempäälä | 2021 |
| Christian Thomé Oy Ab | Helsinki | 1978 |
| Christians Fastighet Ab | Närpiö | 1990 |
| Chydenia Carpark Oy | Jyväskylä | 2005 |
| Cibus Convenience Finland Oy | Helsinki | 2025 |
| Cibus Daily Finland Oy | Helsinki | 2020 |
| Cibus Grocery Finland Oy | Helsinki | 2014 |
| Cibus Retail Finland 1 Oy | Helsinki | 2019 |
| Cindrigo Finland Oy | Espoo | 2025 |
| Circulari Finland Oy | Helsinki | 2022 |
| Cireco Tehdassaari Kiinteistökehitys Oy | Nokia | 2021 |
| Cirrus Oy | Helsinki | 1976 |
| Cisca Oy | Lappeenranta | 2001 |
| Cisti Property Management Oy | Helsinki | 2022 |
| Citia Consulting Oy | Helsinki | 2017 |
| Citinvest Oy | Oulu | 2010 |
| City Construction Oy | Kirkkonummi | 2020 |
| City House LKV Oy | Oitmäki | 2016 |
| City Invest Finland Oy | Riihimäki | 2010 |
| City Kauppapaikat Oy | Seinäjoki | 2020 |
| City Kiinteistönvälitys Oy | Helsinki | 2020 |
| City Pearls GP Oy | Helsinki | 2018 |
| City Renters Oy | Helsinki | 1997 |
| City Village CO-10 Oy | Helsinki | 2019 |
| City Willage Oy | Sipoo | 2007 |
| City-Katto Oy | Helsinki | 1991 |
| City-Rakentajat Oy | Vantaa | 2019 |
| CitySolu Oy | Kokkola | 2025 |