| Pipeteknikk AS | Construction | 1992 |
| Pit Invest AS | | 2023 |
| Pit Lane Autoshine Da | Other services | 1999 |
| Pizza Pizza Telemark Og Vestfold AS | Hospitality | 2014 |
| Pizzahuset Kjørbekk AS | Hospitality | 2023 |
| Pizzanet AS | Hospitality | 2002 |
| Pj-Eiendom AS | Real estate | 2023 |
| Pj-Holding AS | Construction | 2022 |
| PK Bergsli AS | Real estate | 2015 |
| PKJ Holding AS | | 2026 |
| Plan a Sport AS | Wholesale & retail | 2019 |
| Plan Og Eiendom AS | Professional & scientific | 2014 |
| Plan V AS | Professional & scientific | 2002 |
| Plantesalg AS | Wholesale & retail | 2012 |
| Plemm Invest AS | Financial services | 2005 |
| Pless Industri AS | Manufacturing | 2021 |
| Plogen AS | Professional & scientific | 2024 |
| Pluss+Verdier AS | Professional & scientific | 2013 |
| PM Eiendom AS | Real estate | 2005 |
| Point-Of-Care AS | Health & social care | 2023 |
| Polar-Medica AS | Professional & scientific | 2013 |
| Pollen Gård AS | | 2026 |
| Polymertrade AS | Water & waste | 2020 |
| Polymertrade Holding AS | Wholesale & retail | 2020 |
| Polytec-Industribelegg AS | Construction | 2020 |
| Pond 1 AS | Real estate | 2022 |
| Pond 2 AS | Real estate | 2025 |
| Pood AS | Wholesale & retail | 2018 |
| Pood Eiendom AS | Real estate | 2021 |
| Pood Holding AS | Real estate | 2021 |
| Pop Inn AS | Wholesale & retail | 2018 |
| Poppel Eiendom AS | Real estate | 2007 |
| Popup Resalg AS | Wholesale & retail | 2019 |
| Porsgrunnsfestivalen AS | Arts & recreation | 2014 |
| Porsgrunnsvegen 15 AS | Real estate | 2017 |
| Porsgrunnsveien 304 AS | Real estate | 1991 |
| Porstomta II AS | Real estate | 2018 |
| Port-Teknikk AS | Manufacturing | 2012 |
| Port-Teknikk Eiendom AS | Real estate | 2011 |
| Portahead AS | Professional & scientific | 2006 |
| Portspesialisten Grenland AS | Wholesale & retail | 2021 |
| Posthuskåsa AS | Real estate | 2021 |
| Power Connect AS | Professional & scientific | 2017 |
| Power-Link AS | Administrative & support | 2023 |
| Powershaker Da | Wholesale & retail | 2016 |
| Powunit AS | Professional & scientific | 2016 |
| Poxycon AS | Wholesale & retail | 2023 |
| Ppmaler AS | Construction | 2025 |
| Preciso Holding AS | | 2015 |
| Prestasjon AS | Administrative & support | 2026 |
| Prestegårdsgata AS | Real estate | 2018 |
| Prestholt Eiendom AS | Wholesale & retail | 2014 |
| Prestholt Holding AS | Wholesale & retail | 2005 |
| Prestål Eiendom AS | Real estate | 2000 |
| PRG AS | Administrative & support | 2009 |
| Priess Norway AS | Construction | 2025 |
| Prima Landbruk AS | Wholesale & retail | 2024 |
| Primal Products AS | Wholesale & retail | 2026 |
| Prinsessegata 2A AS | Real estate | 2008 |
| Prinsessegaten 14 AS | Real estate | 1947 |
| Prinzip Da | Arts & recreation | 2026 |
| Privatklinikken I Skien AS | Health & social care | 2019 |
| Pro Property Grenland AS | Real estate | 2021 |
| Produktmix AS | Wholesale & retail | 2014 |
| Profftekk AS | Construction | 2025 |
| Profittmaksimering AS | Professional & scientific | 2012 |
| Promedia AS | Professional & scientific | 2021 |
| Prosecure AS | Administrative & support | 2024 |
| Prosjektil Sør AS | Professional & scientific | 2020 |
| Prosolar AS | Energy | 2022 |
| Protect Holding AS | Real estate | 2015 |
| Protektiv AS | Manufacturing | 1991 |
| Provendo AS | Information & communication | 2012 |
| Proweld Industrier AS | Manufacturing | 2013 |
| PRT Capital AS | Administrative & support | 2003 |
| PRT Invest AS | | 2024 |
| PS Interiør AS | Wholesale & retail | 2023 |
| PSC Capital AS | | 2021 |
| PSS Holding AS | Real estate | 2015 |
| Psykiatripartner AS | Health & social care | 2020 |
| Psykologspesialist SSB AS | Health & social care | 2023 |
| PTR AS | Administrative & support | 2012 |
| Pu Invest AS | Real estate | 2020 |
| Pure Elisabeth AS | Arts & recreation | 2020 |
| Pust Holding AS | | 2020 |
| Pyk Holding AS | | 2019 |
| Pål Mathisen Eiendom Ans | Real estate | 2000 |
| Pål Riis AS | Wholesale & retail | 2005 |
| Pølsebu Invest AS | Financial services | 2014 |
| Qualis Regnskap AS | Professional & scientific | 2023 |
| Quatrefoil AS | Real estate | 2005 |
| Quayside AS | | 2019 |
| Quvik AS | Information & communication | 2026 |
| Quvik Holding AS | | 2026 |
| R & M Eiendom AS | Real estate | 2010 |
| R Olaussen Maskinering AS | Manufacturing | 1979 |
| R. Coward Eiendomsinvest AS | Real estate | 2023 |
| R. Coward Invest AS | Real estate | 2023 |
| R. Isaksen Holding AS | Manufacturing | 2005 |
| R2R Norge AS | Real estate | 2023 |