| Christensen Bygg & Eiendom AS | Sandefjord | 2023 |
| Christensen Bygg AS | Risør | 2026 |
| Christensen Bygg Og Utleie AS | Ørje | 2020 |
| Christensen CC Rørservice AS | Stokke | 2015 |
| Christensen Holding AS | Søreidgrend | 2005 |
| Christensen Røyr AS | Slinda | 2023 |
| Christer B Myhre AS | Kodal | 2022 |
| Christer Byggservice AS | Hommersåk | 2023 |
| Christer Desserud AS | Solumsmoen | 2019 |
| Christer Haugen AS | Sørarnøy | 2021 |
| Christer Lenneson | Mysen | 2002 |
| Christer Lie Holding AS | Oslo | 2006 |
| Christer Sundstrøm AS | Alta | 2014 |
| Christeyns AB | Se-113 43 Stockholm | 2025 |
| Christfam AB Nuf | Askim | 2003 |
| Christian Eriksson Holding AS | Oslo | 2023 |
| Christian Hernes Bygg AS | Kolvereid | 2024 |
| Christian Jæger AS | Årnes | 2014 |
| Christian Mussmacher | De-12621 Berlin | 2012 |
| Christian Pallesen Bygg AS | Bø I Telemark | 2020 |
| Christian Pfeiffer Maschinenfabrik GmbH | De-59269 Beckum | 2019 |
| Christian Rør AS | Høvik | 2025 |
| Christian Schumann | Trondheim | 2012 |
| Christiania Blikkenslageri Ans | Oslo | 1996 |
| Christiania Bygg Prosjekt AS | Oslo | 2016 |
| Christiania Eiendom Holding AS | Lysaker | 2005 |
| Christiania Elektrikerbedrift AS | Fjellhamar | 2020 |
| Christiania Entreprenør Og Maskin AS | Oslo | 2015 |
| Christiania Investering AS | Oslo | 2017 |
| Christiania Malerbedrift AS | Oslo | 2017 |
| Christiania Mur & Flis Da | Oslo | 2006 |
| Christiania Murmester AS | Oslo | 2024 |
| Christiania Oppmerking AS | Trollåsen | 2009 |
| Christiania Oppussing AS | Oslo | 2026 |
| Christiania Rørleggerbedrift AS | Oslo | 2013 |
| Christiania Stillas AS | Frogner | 2002 |
| Christiania Stillas Holding AS | Frogner | 2005 |
| Christiania Tekniske AS | Oslo | 2020 |
| Christiania Tre Og Metall AS | Oslo | 2024 |
| Christiania Utemiljø AS | Dokka | 2008 |
| Christiania Ventilasjon AS | Oslo | 2022 |
| Christiania VVS AS | Oslo | 2024 |
| Christiansen & Christiansen Bygg AS | Skien | 2012 |
| Christiansen Bygg AS | Hønefoss | 2011 |
| Christiansen Og Kjenner AS | Vollen | 2015 |
| Christianssand Bygg & Betong AS | Tveit | 2015 |
| Christie Nordang AS | Molde | 1995 |
| Christie Nordang Utvikling AS | Molde | 2016 |
| Christo Bygg, Folkeboden AS | Nesttun | 2007 |
| Christoffer Bergsholm Holding AS | Sandefjord | 2020 |
| Christoffer Hansen Holding AS | Vadsø | 2015 |
| Christoffer Vatle AS | Stathelle | 2026 |
| Christoffersen Bygg Og Takst AS | Skui | 2025 |
| Chrome Eiendom AS | Flateby | 2017 |
| Chrono Kapital AS | Oslo | 2018 |
| Chrost Mati Bygg AS | Hov | 2013 |
| Cib Montering AS | Olsvik | 2015 |
| Cibes Lift Norge AS | Billingstad | 2014 |
| Cibicom Services | 2750 Ballerup | 2023 |
| Cid Bygg AS | Sandnes | 2025 |
| Ciesielstwo Nowoczesne Bartlomiej Ponikiewski | Pl-34-323 Las | 2017 |
| Ciest Metal Oü Nuf | 11415 Harju Maakond | 2013 |
| Cihan Snekkertjenester AS | Drammen | 2026 |
| Cilconset Lda | Pt-2900-276 Setúbal | 2023 |
| Cimc-Tianda Netherlands Coöperatief U.A | Nl-1816Kv Alkmaar | 2022 |
| Cimem S.R.L | 1-80078 Pozzuoli | 2014 |
| Cimota Bygg AS | Oslo | 2012 |
| Cimota Holding AS | Oslo | 2005 |
| Cirkelbygg AS | Åros | 2007 |
| Ciroko Norge Nuf | Tistedal | 2007 |
| Citereja Holding AS | Porsgrunn | 2021 |
| City & Service AS | Oslo | 2011 |
| City Bygg Og Eindom AS | Maura | 2025 |
| City Bygg Sunndal Da | Sunndalsøra | 2011 |
| City Consultants AS | Drammen | 2016 |
| City Contractor AS | Paradis | 2017 |
| City Elektro AS | Oslo | 2003 |
| City Rør AS | Oslo | 2006 |
| City Taktekking AS | Oslo | 1951 |
| City Ventilasjon AS | Maura | 2017 |
| Cityglas Entreprenad I Stockholm AB Nuf | Se-195 70 Rosersberg | 2024 |
| Ciuciu Bygg AS | Finnøy | 2024 |
| Civis AS | Kråkerøy | 2011 |
| CK Bygg AS | Oslo | 2023 |
| CK Entreprenør AS | Sande I Vestfold | 2016 |
| CK Maskin Og Transport AS | Sparbu | 2013 |
| CKJ Steel | 4600 Køge | 2011 |
| CL Bygg & Eiendom AS | Sande I Vestfold | 2016 |
| Cla Holding AS | Rakkestad | 2022 |
| Claessen & Johnsen AS | Ålvundfjord | 2009 |
| Classic Bad AS | Haukeland | 2022 |
| Classic Bygg AS | Bjørkelangen | 2016 |
| Claudio Celiberti T/A Studio Celiberti Nuf | Tw18 1Rx Surrey | 2017 |
| Claudiu AS | Skudeneshavn | 2022 |
| Claussen Elektro AS | Skien | 2021 |
| Claussen Holding AS | Skien | 2018 |
| Clavier Emmanuel Julien Mathieu Nuf | Fr-05600 Guillestre | 2025 |
| Clay Modellling Design Göteborg AB | Se-417 28 Göteborg | 2013 |
| Clean Energy Technologies Norway Nuf | Svelvik | 2017 |
| Clean Tunnel Air International AS | Trondheim | 2006 |