| Con-Form Bergen AS | Kolltveit | 1997 |
| Con-Form Produksjon AS | Orkanger | 1984 |
| Con-Form Strömstad AB | Se 452 94 Strömstad | 2021 |
| Con-Serv AS | Grimstad | 2009 |
| Con-Son Invest AS | Klokkarstua | 2006 |
| Concord Interiør AS | Trondheim | 1999 |
| Condelica AS | Drammen | 2006 |
| Cone 7- Ceramics Workshop AS | Laksevåg | 2021 |
| Connector Subsea Distribution AS | Kokstad | 1998 |
| Conoptica AS | Klæbu | 1985 |
| Conoptica Eiendom AS | Klæbu | 1997 |
| Conpart AS | Skjetten | 2002 |
| Conrads Brenneri AS | Stavanger | 2021 |
| Conrep AS | Mo I Rana | 2021 |
| Consarc Engineering Limited | Lanarkshire Ml1 4Xl Scotland | 2023 |
| Consilium Decor AS | Svelvik | 2015 |
| Conso AS | Helle | 2019 |
| Constairs AS | Gvarv | 2015 |
| Constrind Lda Nuf | 3090-380 Figueira Da Foz | 2017 |
| Construcciones Y Auxiliar De Ferrocarriles S.A. | Es-20200 Beasain, Guipuzcoa | 2019 |
| Construction Equipment Group AS | Sundebru | 2021 |
| Construction Equipment Group Holding AS | Sundebru | 2021 |
| Containertech AS | Bygland | 2007 |
| Containertech Holding AS | Flekkefjord | 2022 |
| Contech Nordic AB Nuf | Se-267 77 Ekeby | 2019 |
| Contek AS | Rakkestad | 2022 |
| Contract Service Nuf | 81-304 Gdynia | 2023 |
| Contribo AS | Hamar | 1994 |
| Control Cutter AS | Tananger | 2010 |
| Control Cutter Rental AS | Tananger | 2018 |
| Controlteam AS | Nesttun | 1998 |
| Conworks Sp.Z.O.O Nuf | Pl-63-842 Pudliszki | 2026 |
| Conzorzio S.B.Z | 42019 Scandiamo (Re) | 2011 |
| Cook Fabrications Limited Nuf | Ct18 7Aw Folkestone, Kent | 2026 |
| Cookiesbyvindenes AS | Rådal | 2020 |
| Cool & Steel Nuf | Fi-23800 Laitila | 2021 |
| Cool Sorption | Dk-2600 Glostrup | 2020 |
| Cooling Partner AS | Solbergelva | 2004 |
| Coolways Norge AS | Fredrikstad | 2019 |
| Coop Norge Industri AS | Oslo | 2000 |
| Coperion GmbH | De-70469 Stuttgart | 2022 |
| Coperion S.R.L. | It-44122 Ferrara | 2025 |
| Copycat AS | Oslo | 1996 |
| Copycat Holding AS | Fornebu | 2021 |
| Cor-Si AS | Kristiansand S | 2020 |
| Cordell Group Limited | Ts18 1Pl Teeside | 2007 |
| Core Integrity AS | Bergen | 2022 |
| Coretryn AS | Bardufoss | 2026 |
| Corinor AS | Bøverbru | 1984 |
| Corner Nanobryggeri AS | Kristiansund N | 2024 |
| Coronet Madrasser AS | Ytre Arna | 2008 |
| Corron Production AS | Bud | 2020 |
| Corvus Energy AS | Nesttun | 2015 |
| Corvus Energy Holding AS | Nesttun | 2018 |
| Costas Siamidis Nuf | Gr-32011 Tanagra Viotia | 2021 |
| Cot Maskinering AS | Nærbø | 2018 |
| Coty Geneva Versoix | Sandefjord | 2013 |
| Couthonsolution AB Nuf | Se-416 51 Göteborg | 2025 |
| Covent AS | Bjerkreim | 2008 |
| Covershield AS | Stokke | 2022 |
| Covr AS | Randaberg | 2022 |
| Cozycup AS | Oslo | 2025 |
| Cozzi Costruzioni S.R.L Nuf | It-84030 Atena Lucana | 2022 |
| Cp.Max Rotortechnik GmbH & Co. KG | De-01099 Dresden | 2026 |
| Cpe Holding AS | Bønes | 2005 |
| CR Service AS | Harstad | 2022 |
| Cracknut AS | Isdalstø | 2015 |
| Cracon AS | Finneidfjord | 2012 |
| Craig Alibone Chocolate AS | Bodø | 2015 |
| Crane Tech AS | Sandnes | 2006 |
| Crantz Cookies AS | Oslo | 2026 |
| Crave Nutrition AS | Trondheim | 2026 |
| Cravings AS | Larvik | 2022 |
| Cray Inc | Wa 98104-2860 Washington | 2007 |
| Cray UK Ltd | London Ec2Y 8Q England | 2007 |
| CRB AS | Jevnaker | 2022 |
| CRC Evans Norway AS | Stavanger | 2025 |
| CRE8 Systems AS | Stavanger | 2010 |
| Creadent AS | Oslo | 2018 |
| Creaone AS | Kristiansand S | 2025 |
| Crear Holding AS | Kongsvinger | 2013 |
| Crema Kaffebrenneri AS | Sandefjord | 1983 |
| Creo Kjøkken AS | Tolvsrød | 2024 |
| Crescere-Holding AS | Klepp Stasjon | 2023 |
| CRH Concrete | 4130 Viby Sjælland | 2010 |
| Criollo Sjokoladebar AS | Drammen | 2018 |
| Crisma Plast & Profilering AS | Sola | 2016 |
| Cronor Service AS | Kløfta | 2021 |
| Cross Country Karlsen AS | Rubbestadneset | 2023 |
| Cross Wrap OY Nuf | Fi-71800 Siilinjärvi | 2024 |
| Crosshjørnet AS | Bjørkelangen | 2000 |
| Cruickshank Support Services Ltd | Peterhead Ab42 1Ld | 2024 |
| Crunch Lab Factory AS | Kristiansand S | 2026 |
| Cryonor AS | Volda | 2009 |
| Crystal Water Norway AS | Oslo | 2015 |
| CS Multimekanisk AS | Urangsvåg | 2022 |
| CSC Service AS | Halsanaustan | 2019 |
| Csub AS | Arendal | 2003 |
| Csub Group Holding AS | Arendal | 2021 |
| Cta Kystteknikk AS | Dyrvik | 2026 |