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| Ullensaker Eiendomsutvikling AS | Kløfta | 2015 |
| Ullensaker Eiendomsutvikling Holding AS | Kløfta | 2014 |
| Ullensaker Holdning AS | Jessheim | 2023 |
| Ullensaker Ventilasjon & Kjøleservice AS | Jessheim | 2024 |
| Ullensvang Bygg AS | Odda | 1987 |
| Ullensvang Entreprenør AS | Nå | 2019 |
| Ullern Bygg AS | Oslo | 2018 |
| Ullern Bygg Vestfold AS | Larvik | 2023 |
| Ullern Entreprenør AS | Båtstø | 2022 |
| Ullern Rør AS | Oslo | 2015 |
| Ullern Rør Nuf | Oslo | 2009 |
| Ullerøy Bygg & Anlegg AS | Skjeberg | 2026 |
| Ullevål Malermesterforretning AS | Ålesund | 1998 |
| Ullrich Holding AS | Kvaløya | 2012 |
| Ulmos GmbH | 64646 Heppenheim (Bergstrasse) | 2011 |
| Ulrich Gläser Montage-Service | De-08297 Zwönitz | 2011 |
| Ulriks Entreprenad AB | Se-686 91 Sunne | 2019 |
| Ulriksen Konstruksjon AS | Kleppstad | 2023 |
| Uls Design AS | Ålesund | 2020 |
| Ulsaker & Gjeile Bygg AS | Dokka | 2013 |
| Ulsakerhaugen Bygg Og Anlegg AS | Dokka | 2022 |
| Ulseth Bygg AS | Melsomvik | 2014 |
| Ulstein Anlegg AS | Hareid | 2018 |
| Ulstein Blikkenslagerverksted AS | Vennesla | 1996 |
| Ulstein Entreprenør AS | Haddal | 2013 |
| Ulstein. AS | Vennesla | 2012 |
| Ultima Rørservice AS | Haslum | 2022 |
| Ultimal AS | Stavanger | 2019 |
| Ultimatebygg AS | Oslo | 2018 |
| Ultra Bygg AS | Trondheim | 2016 |
| Ultra Facility AS | Råde | 2019 |
| Ulven Bjørkli Bygg AS | Hønefoss | 2021 |
| Ulven Skog Og Hage AS | Os | 2024 |
| Ulvene Tømrerservice AS | Jessheim | 2021 |
| Ulvenes Byggservice AS | Hauglandshella | 2022 |
| Ulversøy AS | Randaberg | 2012 |
| Ulversøy Bygg Og Bemanning AS | Fitjar | 2022 |
| Ulverud Mur Og Flis AS | Eidsvoll | 2017 |
| Ulvestad Invest AS | Hylkje | 2005 |
| Ulvesund Elektro AS | Deknepollen | 1999 |
| Ulvesund Holding AS | Deknepollen | 2018 |
| Ulvik & Westgaard Klimaentreprenør AS | Fornebu | 2003 |
| Ulvik VVS AS | Ulvik | 2007 |
| Ulvin Maskin AS | Rennebu | 2016 |
| Ulvås Holding AS | Halden | 2012 |
| Umwelttechnik Und Brunnenbau Wöltjen GmbH | Sortland | 2008 |
| Undal AS | Varhaug | 2011 |
| Under Tak AS | Risør | 2005 |
| Underground City Norway AS | Oslo | 2024 |
| Underhaugsveien 7 AS | Drammen | 2019 |
| Undervannsentreprenøren AS | Porsgrunn | 2011 |
| Underverk Bygg AS | Oslo | 2016 |
| Undheim AS | Molde | 2024 |
| Undheim Maskin AS | Helleland | 2010 |
| Unhjem Holding AS | Kristiansand S | 2022 |
| Uni Bygg AS | Ålesund | 2001 |
| Uni Pur | Dk-8370 Hadsten | 1999 |
| Uni Rørservice AS | Oslo | 2020 |
| Uni Tak AS | Porsgrunn | 2013 |
| Uni Tjenester AS | Stathelle | 2026 |
| Uni-Bygg AS | Voss | 2010 |
| Uni-Tek | Dk-8960 Randers Sø | 2024 |
| Uni-Vent Norway Limited Nuf | Hølen | 2010 |
| Unibep Spolka Akcyjna Nuf | 17-100 Bielsk -Podlaski | 2009 |
| Unibo Bygg AS | Bergen | 2013 |
| Unienergi AS | Hafrsfjord | 2018 |
| Unifix AS | Lørenskog | 2025 |
| Uniflexservice a AS | Strømmen | 2022 |
| Unigrav AS | Hokksund | 2017 |
| Unihouse Spolka Akcyjna Nuf | Pl-17-100 Bielsk Podlaski | 2019 |
| Unik Bad&Bygg AS | Oslo | 2024 |
| Unik Bygg AS | Oslo | 2021 |
| Unik Byggmester AS | Rygge | 2024 |
| Unik Flis AS | Oslo | 2025 |
| Unik Solutions AS | Jessheim | 2023 |
| Unik VVS AS | Nesttun | 1996 |
| Unike Tjenester AS | Oslo | 2024 |
| Unimark Tutaj AS | Råde | 2019 |
| Unimaskin AS | Mo I Rana | 1976 |
| Unimets AS | Vikersund | 2018 |
| Union Bygg Og Malere AS | Oslo | 2023 |
| Union Malere Oslo AS | Finstadjordet | 2024 |
| Union VVS AS | Trondheim | 2022 |
| Unipro AS | Trofors | 1999 |
| Uniqon AS | Stord | 2020 |
| Unique Bygg AS | Solbergelva | 2016 |
| Unique Network Solutions Ltd | Milnrow Ol16 4Eq | 2024 |
| Uniqus AS | Kristiansand S | 2021 |
| Unirør AS | Skien | 2023 |
| Unisol Holding AS | Bybrua | 2014 |
| Unitas Invest AS | Oslo | 2021 |
| Uniteam Project AS | Hagan | 2022 |
| Unitec AS | Heimdal | 2025 |
| Unitech Wireless (Tamilnadu) Private Limited | In-110017 New Dehli | 2012 |
| United Pipeline Systems International Inc | Colorado 81303 | 2017 |
| Uniteh | Hr-10040 Zagreb | 2012 |
| Unitek AS | Trondheim | 2020 |
| Unitek Elektro AS | Billingstad | 2023 |
| Uniteq Engineering Nuf | Nl-6002 Weert | 2022 |