| Osm Invest AS | Financial services | 2005 |
| Ossihuset AS | Education | 2026 |
| Ossy AS | Financial services | 2013 |
| Ost & Vin AS | | 2026 |
| Osta AS | Real estate | 2017 |
| Ostehuset Øst AS | Hospitality | 2007 |
| Ostereidet Holding AS | Financial services | 2005 |
| Osv Sivertsen AS | Construction | 1985 |
| Otd AS | Administrative & support | 2019 |
| Otech Marine Services Norway AS | Mining & quarrying | 2016 |
| Oter Entertainment AS | Information & communication | 2023 |
| Othala AS | Real estate | 2024 |
| Otic AS | Real estate | 2011 |
| Otillio AS | Mining & quarrying | 2005 |
| Otire Invest AS | Professional & scientific | 2014 |
| Otnem Eiendom AS | Real estate | 1984 |
| Ottesen & Zahl AS | Arts & recreation | 2013 |
| Ouch Burger Løkkeveien AS | Hospitality | 2023 |
| Ouch Forus AS | Hospitality | 2026 |
| Outfront AS | Information & communication | 2020 |
| Ovalen Parkering AS | Real estate | 2017 |
| Ovalen Sandnes AS | | 2014 |
| Ove Idsøe Holding AS | Financial services | 2005 |
| Ove Pedersen Shipping AS | | 2026 |
| Oveheitmann AS | | 2024 |
| Overflategruppen AS | | 2024 |
| Overseas Consultants AS | Professional & scientific | 1991 |
| Overseas Renewable AS | Professional & scientific | 2021 |
| Ovienne AS | | 2026 |
| Ovrkomme AS | Information & communication | 2023 |
| Oxionic AS | Wholesale & retail | 2015 |
| Oxyno AS | Professional & scientific | 2026 |
| Oz Midco AS | Mining & quarrying | 2013 |
| Ozio AS | Real estate | 2006 |
| P & P Eiendom AS | Real estate | 1998 |
| P & R Kaada Eiendom AS | Real estate | 1970 |
| P H Skulevold AS | Professional & scientific | 2009 |
| P Wærp Agentur AS | Wholesale & retail | 1986 |
| P26VOGE AS | Hospitality | 2024 |
| P53 Invest AS | Real estate | 2018 |
| P95 Bolig AS | Real estate | 2026 |
| Paahjul AS | Other services | 2013 |
| Pabaconsult AS | Professional & scientific | 2021 |
| Paca AS | Hospitality | 2019 |
| Paeco AS | Professional & scientific | 2019 |
| Pai Mei AS | Hospitality | 2024 |
| Paja Holding AS | | 2005 |
| Paleblue AS | Information & communication | 2013 |
| Palia AS | Financial services | 2006 |
| Palmark Offshore AS | Administrative & support | 2001 |
| Palmen Bar AS | Hospitality | 2025 |
| Palmera House AS | Construction | 2025 |
| Paludan AS | | 2020 |
| Palé AS | Hospitality | 2022 |
| Panda Arkitektur AS | Professional & scientific | 2023 |
| Panda AS | Wholesale & retail | 2012 |
| Panda Invest Holding AS | Financial services | 2016 |
| Panduit Eeig | Professional & scientific | 2003 |
| Pangaea Eiendom AS | Real estate | 2014 |
| Panogram AS | Professional & scientific | 2019 |
| Panzer Invest AS | | 2021 |
| Papas Pizzeria AS | Hospitality | 2021 |
| Paper Plane AS | | 2021 |
| Papereasy AS | Wholesale & retail | 2012 |
| Pappagøye AS | | 2014 |
| Par Invest Holding AS | Wholesale & retail | 2017 |
| Par Premium Collection AS | Wholesale & retail | 2015 |
| Parachuting Beavers AS | Professional & scientific | 2020 |
| Paradiddel AS | | 2022 |
| Paradim AS | Information & communication | 2007 |
| Paradis Boligutvikling 1 AS | Real estate | 2015 |
| Paradis Interiør AS | Professional & scientific | 2024 |
| Paradis Legesenter AS | Health & social care | 2023 |
| Paradis Maskinutleie AS | Construction | 2019 |
| Paradis Ny AS | Real estate | 2009 |
| Paradis Senter AS | Real estate | 2016 |
| Paradis Stasjon Bolig AS | Real estate | 2020 |
| Paradisveien 87 AS | Real estate | 2018 |
| Parameter AS | Real estate | 2004 |
| Paratus AS | Professional & scientific | 2003 |
| Parco Web&Consulting Da | Information & communication | 2012 |
| Parentes AS | Professional & scientific | 2012 |
| Parentes Holding AS | Professional & scientific | 2021 |
| Parin AS | Administrative & support | 2021 |
| Parka Productions AS | Information & communication | 2018 |
| Parkportalen AS | Real estate | 2010 |
| Parkveien Invest AS | Professional & scientific | 2001 |
| Parsai AS | Information & communication | 2026 |
| Parsellen AS | Real estate | 2022 |
| Parterapeutene AS | Education | 2006 |
| Partner Consult AS | Professional & scientific | 1998 |
| Partners Eiendom AS | Real estate | 1996 |
| Partrederiet Clipper Mars II Da | Transport & logistics | 2023 |
| Partrederiet Clipper Neptun Da | Transport & logistics | 2024 |
| Partrederiet Vlgc Da | Transport & logistics | 2018 |
| Partum MB! AS | Arts & recreation | 2007 |
| Pasha Restaurant AS | Hospitality | 2025 |
| Pastabakeren AS | Hospitality | 1993 |
| Patagonia Holding AS | Hospitality | 2015 |
| Pathi Holdings AS | | 2020 |