| Odden Klær AS | Wholesale & retail | 1984 |
| Odden Mat AS | Wholesale & retail | 2018 |
| Odden Trening AS | Arts & recreation | 2026 |
| Oddity AS | | 2025 |
| Oh Trondsen Holding AS | | 2021 |
| Ohoi AS | Administrative & support | 2019 |
| Ola Lundberg AS | Real estate | 2026 |
| Olaf Tønnevold & Sønner AS | Real estate | 1943 |
| Olav Lindstøl AS | Construction | 1983 |
| Olmar AS | Professional & scientific | 2005 |
| Olsenbygg AS | Construction | 2008 |
| Olsenbygg Grimstad AS | Construction | 2012 |
| Omland Group AS | | 2025 |
| Omre Industripark 2 AS | Real estate | 2025 |
| Omre Industripark AS | Real estate | 2017 |
| Omtek AS | Professional & scientific | 2025 |
| Onarheimslia AS | | 2021 |
| Optikkhuset Grimstad AS | Wholesale & retail | 1996 |
| Ordbruk AS | Health & social care | 2004 |
| Ordrik AS | Real estate | 2010 |
| Os Wind AS | Administrative & support | 2025 |
| Oscillator AS | | 2022 |
| Ositos AS | | 2021 |
| Ottersland Holding AS | | 2026 |
| Outlet Kids AS | Wholesale & retail | 2019 |
| Overland Maskin AS | Construction | 2002 |
| P Nordby & Co AS | Professional & scientific | 2000 |
| P.S. Windegaard AS | Professional & scientific | 2006 |
| P2 Invest AS | Real estate | 2019 |
| Pa-Systemer AS | Wholesale & retail | 2014 |
| Pacific Capital AS | Professional & scientific | 2006 |
| Pafoal AS | Professional & scientific | 2023 |
| Palazzo Norway AS | Administrative & support | 2016 |
| Pama Eiendom AS | Real estate | 2009 |
| Pang Invest AS | | 2024 |
| Paralov AS | Information & communication | 2025 |
| Paralov Holding AS | | 2025 |
| Parateq AS | Arts & recreation | 2021 |
| Parkveien 37 AS | Real estate | 2008 |
| Parlow Holding AS | | 2005 |
| Partner-Bygg AS | Wholesale & retail | 2010 |
| Partsrederiet Astor Ans | Agriculture & fishing | 2000 |
| Pearl Journeys AS | Administrative & support | 2017 |
| Pelican Aqua Management AS | Professional & scientific | 2026 |
| Pepadea AS | Wholesale & retail | 2026 |
| Per Kristian Borge AS | Construction | 2025 |
| Perc AS | Real estate | 2024 |
| Perla Invest AS | Real estate | 2024 |
| Persiakiosken Ans | Wholesale & retail | 1992 |
| Personalet AS | Administrative & support | 2025 |
| Pettersen Todnem Holdning AS | | 2026 |
| PGT Eiendom AS | Real estate | 2005 |
| PGT Invest AS | Real estate | 1997 |
| PH Eiendom AS | Real estate | 2024 |
| PH Maskin AS | Construction | 2022 |
| Pilen Invest AS | Professional & scientific | 2013 |
| Pinea AS | Real estate | 2026 |
| Pioneer Robotics AS | Information & communication | 2017 |
| Pipefiks Grimstad AS | Construction | 2024 |
| PJ Invest AS | Real estate | 2021 |
| Pja Holding AS | Construction | 2009 |
| Plantedottir AS | Wholesale & retail | 2022 |
| Plato Group AS | Professional & scientific | 2013 |
| Plush Badger Music AS | Arts & recreation | 2002 |
| Polo Holding AS | Real estate | 2004 |
| Portal AS | Transport & logistics | 2024 |
| Postgården Grimstad AS | Real estate | 2001 |
| Praktiske Tjenester AS | Administrative & support | 2013 |
| Primatec AS | Wholesale & retail | 1997 |
| Primiticus AS | | 2026 |
| Pro Med Professional Medics AS | Wholesale & retail | 2019 |
| Progres AS | Real estate | 2020 |
| Prosjekthuset AS | Professional & scientific | 2015 |
| Prospectsim AS | Information & communication | 2023 |
| Protu AS | Information & communication | 2000 |
| PS Anlegg AS | Construction | 2013 |
| PS Skog AS | Agriculture & fishing | 2019 |
| PS Utvikling AS | Construction | 2013 |
| PST Holding AS | Real estate | 2013 |
| Psykolog Tone Nathalie Meberg AS | Health & social care | 2011 |
| Psykologtjenesten Da | Health & social care | 2022 |
| PT Studio WAY2ENDURANCE AS | Education | 2021 |
| Pto 82 AS | Real estate | 2020 |
| PWM Holding AS | Real estate | 2010 |
| Pål Rågår AS | Real estate | 2025 |
| Qest Invest AS | Health & social care | 2005 |
| Qrant AS | Other services | 2020 |
| Quality Brew AS | Wholesale & retail | 2017 |
| R. O. Holding AS | Manufacturing | 2013 |
| Ra & P AS | Real estate | 2007 |
| Rabaldergrimstad AS | Wholesale & retail | 2021 |
| Raulandsgrenda AS | Real estate | 2007 |
| Re-Freshing AS | Other services | 2023 |
| Rebel Production AS | Arts & recreation | 2018 |
| Red Anvil GmbH | Wholesale & retail | 2004 |
| Reddal AS | Mining & quarrying | 1989 |
| Reddal Fellespakkeri SA | Wholesale & retail | 2004 |
| Reddal Storkiosk Ans | Wholesale & retail | 1991 |
| Reddal Vanningslag SA | Agriculture & fishing | 1977 |
| Reddalsveien 35 AS | Manufacturing | 2007 |