| Otta Skifer AS | Otta | 1998 |
| Ottadalen Mølle SA | Lom | 1976 |
| Ottar AS | Finnsnes | 2015 |
| Ottar Statle AS | Leknes | 2012 |
| Ottaskifer Holding AS | Otta | 2022 |
| Ottem Recycling AS | Sunndalsøra | 2021 |
| Otteren Jewellery AS | Sandnes | 2023 |
| Otterlei Industries AS | Arendal | 2018 |
| Otterlei Investment AS | Oslo | 2023 |
| Otterlei Mekanisk & Rør AS | Brattvåg | 2024 |
| Otterlei Service AS | Ellingsøy | 2025 |
| Otto H AS | Molde | 2013 |
| Otto Jenssens Bakeri AS | Mehamn | 1987 |
| Ottosen AS | Kristiansand S | 2018 |
| Ottosen Invest AS | Tveit | 2020 |
| Otu Holding AS | Kolnes | 2018 |
| Ourobouros AS | Oslo | 2021 |
| Oury Diallo Diallo Systue AS | Oslo | 2023 |
| Ousdal Service AS | Lindesnes | 2025 |
| Outboardservice Sande AS | Sande I Vestfold | 2014 |
| Outdoor Design AS | Nærbø | 2021 |
| Ovag AS | Sæbø | 2007 |
| Ovatronic AS | Søgne | 2020 |
| Ovdin AS | Melhus | 2015 |
| Ove Øen Blikkenslager & Taktekker AS | Bergen | 1983 |
| Overflate Teknikk AS | Frekhaug | 2025 |
| Overflatetjenester AS | Larvik | 2018 |
| Overflatetjenester Numedal AS | Tunhovd | 2026 |
| Overhalla Betongbygg AS | Overhalla | 1996 |
| Overhalla Gruppen AS | Overhalla | 2005 |
| Overhalla Mekaniske AS | Overhalla | 1988 |
| Ovun AS | Åndalsnes | 1992 |
| Ovun Holding AS | Åndalsnes | 2014 |
| Owens-Corning Britinvest Ltd | Oslo | 2007 |
| Owens-Corning Veil UK Ltd | Oslo | 2007 |
| Oxenøen Marina Drift AS | Fornebu | 2019 |
| Oxin SRL Norway Branch Nuf | It-31013 Camavilla Di Codognè | 2018 |
| Oxtrade Contract S.R.L. Norway | Ro-547367 Corunca | 2019 |
| Oxvold Invest AS | Trondheim | 2008 |
| OY Paxteam Ltd | 21260 Raisio | 2015 |
| Oyster Thermal AS | Oslo | 2016 |
| Ozeta AS | Kristiansand S | 2020 |
| Ozone Skandinavia AS | Oslo | 1995 |
| Olsen Nauen Klokkestøperi AS | Barkåker | 1986 |
| Opsal Betong AS | Ørsta | 1987 |
| Os Maskinering Haugland og Mo ANS | Os | 1981 |
| P Dahl Elektronik & Data AS | Kirkenær | 2003 |
| P Juls Sandvig AS | Ålesund | 2018 |
| P Juls Sandvig Eiendom AS | Ålesund | 1987 |
| P-Form AB | 777 60 Söderbäcke | 2013 |
| P-O Lundbergs Svetsposition AB | Mysen | 2008 |
| P. Hansson Konsult & Konstruktion AB | Se-598 32 Vimmerby | 2022 |
| P.E. Labellers S.P.A | It-46047 Porto Mantovano (Mn) | 2019 |
| P.Kolbjørnsen AS | Haugesund | 2025 |
| P60 Drift AS | Hønefoss | 1997 |
| Pa Investment AS | Bergen | 2011 |
| Pa'Hy Es Tarsa BT. | 1118 Budapest | 2006 |
| Paal Hage Holding AS | Lier | 2005 |
| Paattimaakarit | Fi-21200 Raiso | 2018 |
| Pac Skrettingland AS | Bryne | 2005 |
| Pacific Marine Batteries Pty. Ltd Nuf | Osborne, Sa 5017 | 2024 |
| Pacific Salmon AS | Kirkenes | 2022 |
| Pacificpeps Norway AS | Langevåg | 2021 |
| Paddeberget Holding AS | Stavern | 2019 |
| Paddå AS | Torvastad | 2000 |
| Paf-Consulting Abp, Norwegian Branch Office Nuf | 22 101 Mariehamn, Åland | 2016 |
| Paint Holding AS | Oslo | 2020 |
| Paintz AS | Oslo | 2024 |
| Paka Solutions AS | Frei | 2025 |
| Pal SRL | It-31047 Ponte Di Piaveos (Treviso) | 2020 |
| Palfinger Marine Norway AS | Nesttun | 1991 |
| Palfinger Marine Norway Holding AS | Nesttun | 2022 |
| Palfinger Marine Safety AS | Seimsfoss | 2009 |
| Palident AS | Haugesund | 2019 |
| Pall Intressenter AS | Oslo | 2023 |
| Pall-Rep Da | Skånevik | 1997 |
| Palla Pharma Norway AS | Kragerø | 2016 |
| Palla Pharma Norway Holding AS | Kragerø | 2017 |
| Pallan Søm Ans | Lillehammer | 1992 |
| Palle Karm Og Kassefabrikken AS | Dalekvam | 1994 |
| Pallefabrikken Alta AS | Alta | 2025 |
| Pallefabrikken Halsa AS | Halsa | 1996 |
| Pallegrossisten AS | Dalekvam | 1994 |
| Pallesen Sveis Ans | Bryne | 1995 |
| Pallesen Sveis AS | Kleppe | 1996 |
| Palm Tree Design AS | Skjærhalden | 2023 |
| Pals AS | Billingstad | 1939 |
| Pama S.P.A. Nuf | It-38068 Rovereto (Tn) | 2025 |
| Pan Group AS | Oslo | 2021 |
| Paname Gruppen AS | Oslo | 2022 |
| Paname Lab AS | Oslo | 2022 |
| Paname Shop AS | Oslo | 2022 |
| Pane E Circo AS | Oslo | 2026 |
| Panpac Engineering | Dk-9490 Pandrup | 2012 |
| Panterra AS | Arendal | 2013 |
| Panzerprint AS | Oslo | 2005 |
| Papa Lås AS | Holmestrand | 2026 |
| Papa Mios International AS | Lillesand | 2003 |
| Papela AS | Alta | 2022 |
| Paperwork AS | Drøbak | 2000 |