| Pentex AS | Construction | 1976 |
| PGM Service AS | Construction | 2020 |
| Pharmatech AS | Manufacturing | 2002 |
| PKM Holding AS | | 2013 |
| Plankebyen Dekksenter AS | Other services | 2024 |
| Plankebyen Regnskap AS | Professional & scientific | 2025 |
| Prana Henriksen AS | Education | 2021 |
| Prana Holding AS | Financial services | 2022 |
| Prateriet Logopedsenter AS | Health & social care | 2014 |
| Prestelandet Boligutvikling AS | Real estate | 2015 |
| Prisguider AS | Information & communication | 2026 |
| Pro One AS | Wholesale & retail | 2012 |
| Prokon Entreprenør AS | Professional & scientific | 2014 |
| Prosjekt 1 AS | Professional & scientific | 2022 |
| Psykiater Knut Martinsen Holding AS | Health & social care | 2025 |
| Psykolog Terje Torp AS | Health & social care | 2020 |
| Pura Invest AS | | 2025 |
| Qmaxi Holding AS | | 2022 |
| Quiel Qonsulting AS | Professional & scientific | 2021 |
| R Rostad Holding AS | Real estate | 2018 |
| Racing 4 Fun AS | Wholesale & retail | 2011 |
| Ramo El-Engros AS | Wholesale & retail | 2018 |
| Ramsjø AS | Manufacturing | 2023 |
| Raspberry Holding AS | Professional & scientific | 2020 |
| Reise Og Konferanseservice AS | Administrative & support | 2004 |
| Rekustad Gård Da | Agriculture & fishing | 2008 |
| RG Byggentreprenør AS | Construction | 2023 |
| Richy Invest AS | Real estate | 2026 |
| Richy Motor AS | Wholesale & retail | 2019 |
| Right Arbeidsklær AS | Manufacturing | 2022 |
| Right Bemanning AS | Administrative & support | 2012 |
| Right Bygg Og Vaktmestertjenester AS | Construction | 2023 |
| Right Drift AS | Administrative & support | 2022 |
| Right Holding AS | Administrative & support | 2022 |
| Right Invest AS | | 2026 |
| Rikter Svendsen AS | Wholesale & retail | 1926 |
| Roa Holding AS | | 2005 |
| Rolf Andreassen AS | Construction | 1992 |
| Rolf Andreassen Eiendom AS | Construction | 2011 |
| Rolf Andreassen Holding AS | Construction | 2005 |
| Rolvsøy Bil & Båtpleie AS | Other services | 2020 |
| Rolvsøy Bygde Service Da | Construction | 2008 |
| Rolvsøy Elektriske AS | Construction | 2026 |
| Rolvsøy Fysioterapi AS | Health & social care | 1989 |
| Rolvsøy Legekontor Da | Health & social care | 2009 |
| Rolvsøy Rør AS | Construction | 2025 |
| Rolvsøy Ølverksted AS | Manufacturing | 2022 |
| Rosenborgveien 3 AS | Real estate | 2015 |
| Rådalen Eiendomsutvikling AS | Real estate | 2019 |
| Råkollveien 60 AS | Real estate | 2024 |
| Rørleggermester Per a. Mathisen AS | Construction | 2007 |
| Saddler Scandinavia AB Norsk Avdeling Av Utenlandsk Foretak Nuf | Wholesale & retail | 2002 |
| Sahlin & Rønneberg Optikk AS | Health & social care | 2024 |
| Salg AS | Real estate | 2010 |
| Saxe & Omberg Investment AS | Financial services | 2022 |
| Saxegård Eiendom AS | Real estate | 1998 |
| Scandic Consulting Da | Wholesale & retail | 2003 |
| Scandinavian Security Design Da | Manufacturing | 2002 |
| Schei Invest Limited Nuf | | 2011 |
| SD Malerservice AS | Construction | 2020 |
| Seda Prosjekter AS | Real estate | 2014 |
| Segmentus AS | Information & communication | 2023 |
| Seiersborg Videregående Skole Fredrikstad AS | Education | 2006 |
| Seljeveien 1 AS | Real estate | 2026 |
| Seljeveien 3 AS | Real estate | 2026 |
| Seljeveien 5 AS | Real estate | 2026 |
| Seljeveien 8 AS | Real estate | 2021 |
| Semmec AS | Manufacturing | 2020 |
| Sense Boligstyling AS | Professional & scientific | 2016 |
| Sense Bygg AS | Construction | 2019 |
| Seut Brygge AS | Real estate | 2010 |
| SGD AS | Arts & recreation | 2017 |
| Sictra AS | Information & communication | 2004 |
| Silent Disco Norge AS | Administrative & support | 2023 |
| Silje's Barn Og Utstyr AS | Wholesale & retail | 2006 |
| Simeon Norge AS | Transport & logistics | 2023 |
| Sirius Company Nuf | Wholesale & retail | 2004 |
| Sivløkka 6 AS | Real estate | 2017 |
| Sivløkka 7 AS | Real estate | 2018 |
| Skarshaug Bygg AS | Construction | 2022 |
| Skeidar Fredrikstad AS | Wholesale & retail | 1996 |
| Smart Økonomi AS | Professional & scientific | 2014 |
| Smart Økonomi AS | Professional & scientific | 2025 |
| Smartnæss AS | Professional & scientific | 2016 |
| Sol Orkan AS | Construction | 2024 |
| Solberg Gulv Industribelegg AS | Construction | 1988 |
| Solcellespesialisten AS | Construction | 2022 |
| Solid Eiendom AS | Real estate | 2004 |
| Solid Entreprenør AS | Construction | 1997 |
| Solid Gruppen AS | Construction | 2005 |
| Solid Næringseiendom AS | Real estate | 2000 |
| Soliveien 42 AS | Real estate | 2008 |
| Solliveien 11 AS | Real estate | 2012 |
| Solstrøm AS | Hospitality | 2014 |
| Sonark AS | Professional & scientific | 2025 |
| SPABUTIKK1.NO AS | Wholesale & retail | 2002 |
| Spacio AS | Information & communication | 2022 |
| Spinn AS | Real estate | 1995 |
| Sportrehab AS | Health & social care | 2011 |
| SSP Holding AS | Manufacturing | 2021 |