| Olav Brattland Eiendom AS | Mo I Rana | 2014 |
| Olav Brattland Holding AS | Mo I Rana | 2014 |
| Olav Eigeland AS | Lillesand | 1991 |
| Olav Eigeland Eiendom AS | Lillesand | 2010 |
| Olav Erik Hagen AS | Stryn | 1993 |
| Olav Fossen AS | Hommelvik | 2005 |
| Olav Hjelmeset AS | Sandane | 2025 |
| Olav Hjelmeset AS | Sandane | 2000 |
| Olav Hovde AS | Brumunddal | 2005 |
| Olav Lindberg AS | Gjesåsen | 2016 |
| Olav Lindstøl AS | Grimstad | 1983 |
| Olav Magne Gorseth AS | Trondheim | 2017 |
| Olav O. Hæreid AS | Årdalstangen | 1988 |
| Olav Solberg AS | Oppdal | 1986 |
| Olav Solvang AS | Dalen | 1996 |
| Olav Wigestrand AS | Stavanger | 2024 |
| Olavsen Invest AS | Bodø | 2023 |
| Olczak Ireneuesz Olczak | 42612 Tarnowskie Gory | 2005 |
| Olda Bygg AS | Våler I Østfold | 2019 |
| Olden Bygg Og Vaktmesterservice AS | Steinsdalen | 2021 |
| Olden Rør AS | Olden | 1986 |
| Olden Varme AS | Førresfjorden | 2019 |
| Olderfjord Brøyteservice AS | Kleppstad | 2019 |
| Ole Bror Bentsen AS | Lier | 2003 |
| Ole Christian Løne AS | Skulestadmo | 2015 |
| Ole Dalen AS | Røn | 2002 |
| Ole E. Sønvisen AS | Tverrelvdalen | 2018 |
| Ole F Suhr AS | Alta | 2011 |
| Ole Fjermedal Holding AS | Vennesla | 2013 |
| Ole Håkon Lofthus AS | Etnedal | 2016 |
| Ole J Hagen Maskin AS | Porsgrunn | 2021 |
| Ole Jakob Ferkingstad Maskin AS | Åkrehamn | 2019 |
| Ole Johan Lund-Johansen | Halden | 2008 |
| Ole Jonny Grønbrekk AS | Heggedal | 2010 |
| Ole Jonny Madsen Maskinentreprenør AS | Porsgrunn | 1976 |
| Ole K Olsen Bygg AS | Marnardal | 2023 |
| Ole Lepsøe Bygg AS | Blomsterdalen | 2017 |
| Ole Liljebakk AS | Narvik | 2001 |
| Ole Loga AS | Lysaker | 2023 |
| Ole M. Almeli AS | Dal | 1987 |
| Ole Markussen Og Sønner AS | Fotlandsvåg | 1994 |
| Ole Morten Furuseth AS | Halden | 2005 |
| Ole Og Tores Rørservice AS | Kragerø | 2004 |
| Ole Oppistov AS | Stavanger | 2016 |
| Ole P. Bakken AS | Ålen | 1975 |
| Ole Petter Holm AS | Birkeland | 2018 |
| Ole Petter Linjord AS | Fossdal | 2018 |
| Ole Petter Strømme AS | Vinje | 2005 |
| Ole Pål Nesttun Malerfirma AS | Nesttun | 1989 |
| Ole Robert Holter AS | Hvasser | 1983 |
| Ole Sivert Bomo AS | Snåsa | 2021 |
| Ole Sivertsen AS | Trondheim | 1976 |
| Ole TH. Sandvik AS | Dyrvik | 2007 |
| Ole Tiller AS | Skaun | 2022 |
| Ole Tom Eger Fjellsprenging AS | Revetal | 2011 |
| Ole-Anders Lien AS | Stavsjø | 2022 |
| Ole-Helge Solstad AS | Sørbøvåg | 2014 |
| Ole-Kristian Meland AS | Agdenes | 2014 |
| Olear Da | Dokka | 2018 |
| Olebakken Maskin AS | Dokka | 2021 |
| Oleg R&B AS | Lakselv | 2017 |
| Oleg Raudsepp AS | Lakselv | 2013 |
| Olehus AS | Stavanger | 2016 |
| Olehus Montasje AS | Stavanger | 2024 |
| Olejarz-Malerne AS | Oslo | 1999 |
| Olektro AS | Namdalseid | 2021 |
| Olendt AS | Oppdal | 2022 |
| Olene Holding AS | Veavågen | 2023 |
| Oleochem Project Management Ltd | Aberdeen Ab23 8Jx Scotland | 2023 |
| Oles Invest & Design AS | Drammen | 2012 |
| Oles Smedforretning | Dk-9600 Aars | 2016 |
| Olesrud AS | Tinn Austbygd | 2018 |
| Olga Baumgärtner Myhome | De-74613 Öhringen | 2022 |
| Olian Holding AS | Årnes | 2019 |
| Olimb Anlegg AS | Råde | 2011 |
| Olimb Group AS | Råde | 2011 |
| Olimb Holding AS | Råde | 2011 |
| Olimb Rørfornying AS | Råde | 2011 |
| Olimb Rørfornying Øst AS | Sem | 2023 |
| Olimb Rørinspeksjon Bergen AS | Nesttun | 2021 |
| Olimstad Holding AS | Arendal | 2023 |
| Olis VVS & Gass Service AS | Oslo | 1990 |
| Oljestein AS | Ålesund | 2026 |
| Olle Grönvall Kulturbygg | Se-312 95 Laholm | 2026 |
| Ollivers Byggservice AS | Korsvegen | 2026 |
| Olma Byggentreprenør AS | Bryne | 2023 |
| Olof Sundström Installation | Se-39477 Kalmar | 2020 |
| Olores Holding AS | Drammen | 2010 |
| Olreda Nuf | 94105 | 2013 |
| OLS1VVS AS | Mjøndalen | 2018 |
| Olsborgs Snekkerservice AS | Kvaløya | 2017 |
| Olsbø & Paulsen AS | Ålesund | 1985 |
| Olsen & Fardal AS | Sæbøvågen | 2008 |
| Olsen & Korsmo Parkettsliperi AS | Oslo | 2000 |
| Olsen & Nordhavn Varmepumpeservice AS | Borgenhaugen | 2021 |
| Olsen & Sønn Varmepumpeservice AS | Klavestadhaugen | 2019 |
| Olsen & Wallum AS | Larvik | 2023 |
| Olsen Asfalt AS | Avaldsnes | 2026 |
| Olsen Blikk & Montasje AS | Råde | 2014 |
| Olsen Bryggeservice AS | Froland | 2025 |