| Pretec Group AS | Wholesale & retail | 2020 |
| Prima Trykk AS | Manufacturing | 2014 |
| Prima Trykk Holding AS | Manufacturing | 2013 |
| Prima-Eiendom AS | Real estate | 2014 |
| Pro Auto Bilskade AS | Other services | 2024 |
| Proff Bygg & Eiendom AS | Construction | 2018 |
| Profit AS | Information & communication | 2017 |
| Prosjekt Løvetann Da | Health & social care | 2003 |
| PRS Eiendom AS | Real estate | 1988 |
| Psykolog Palle Johansson Nuf | Health & social care | 2017 |
| PT Bygg & Eiendom AS | Real estate | 2021 |
| Pure Joy AS | Health & social care | 2012 |
| R.A. Service & Vedlikehold AS | Manufacturing | 2020 |
| Rakkestad Eiendom AS | Real estate | 1998 |
| Ready Communication AS | Information & communication | 2024 |
| Rent Og Pent Østfold AS | Administrative & support | 2016 |
| Rich Bar AS | Hospitality | 2013 |
| Roligheten Boligutleie AS | Real estate | 2026 |
| Rom Konsult Holding | Information & communication | 2005 |
| Rom Konsult Norge AS | Professional & scientific | 1996 |
| Romnes Sarpsborg AS | Wholesale & retail | 2020 |
| Rpov - Renholdspartner Oslo Og Viken AS | Administrative & support | 2022 |
| RSP Consulting AS | Health & social care | 2025 |
| Ryesvei 2B AS | Real estate | 2013 |
| Rynningen AS | Financial services | 2017 |
| Rønning Eiendom AS | Real estate | 1999 |
| Rørlegger G. Andersen AS | Construction | 2008 |
| Saap Eiendom AS | Real estate | 1983 |
| Saap Holding AS | Wholesale & retail | 2020 |
| Sarpsborg Bilsenter AS | Wholesale & retail | 1992 |
| Sarpsborg Bygg Og Eiendomsutvikling AS | Construction | 2011 |
| Sarpsborg Dekk AS | Wholesale & retail | 2022 |
| Sarpsborg Marina AS | Transport & logistics | 2014 |
| Sarpsborg Metall AS | Wholesale & retail | 1981 |
| Sarpsborg Motor AS | Wholesale & retail | 2001 |
| Sarpsborg Rør Og Sveiseservice AS | Construction | 2002 |
| Sarpsborg Squashsenter AS | Arts & recreation | 2012 |
| Sarpsborgfestivalen AS | Arts & recreation | 2015 |
| Scancon AS | Professional & scientific | 2011 |
| Scandinavian Appliances AS | Wholesale & retail | 2003 |
| Schnellfahrer Gruppen AS | Administrative & support | 2016 |
| Schrøder Kvisler Holding AS | | 2026 |
| Scoaam Holding AS | Real estate | 2026 |
| Senter Landbruksverksted AS | Wholesale & retail | 1966 |
| SG Operations AS | Real estate | 2026 |
| Signal Bygg AS | Construction | 2021 |
| Signal Entreprenør Holding AS | Construction | 2021 |
| Sigvartsen Transport AS | Transport & logistics | 1984 |
| Simensen Mekaniske AS | Manufacturing | 2022 |
| Skandinavisk Markedsmedia AS | Information & communication | 2007 |
| Skarpnord Golf Products AS | Manufacturing | 2021 |
| Skarpnord Invest AS | Manufacturing | 2020 |
| Skauen Invest AS | Wholesale & retail | 2005 |
| Skjeberg Bilopphuggeri AS | Wholesale & retail | 2015 |
| Skjeberg Treningssenter AS | Arts & recreation | 2011 |
| Skjebergveien 154 AS | Real estate | 2017 |
| Skjebergveien 25 AS | Real estate | 2007 |
| SLG Invest AS | | 2022 |
| Sløyfeveien Eiendom AS | Real estate | 2023 |
| Sma Prosjekt AS | Professional & scientific | 2006 |
| Smelteverket Eiendom AS | Real estate | 2002 |
| Smeta Holding AS | Real estate | 1994 |
| Smidig Levert AS | Transport & logistics | 2024 |
| Soba Bemanning | Administrative & support | 2008 |
| Soft Topco AS | Information & communication | 2018 |
| Solbyen Anlegg AS | Construction | 2025 |
| Solbyen Utleie AS | Administrative & support | 2022 |
| Sono Holding Norge AS | Wholesale & retail | 2010 |
| Sono Norge AS | Wholesale & retail | 2007 |
| Sono Norop AS | Wholesale & retail | 2005 |
| Sparta Holding AS | | 2004 |
| Spoonhill AS | Professional & scientific | 2026 |
| Sportswear AS | Wholesale & retail | 2023 |
| ST Bygg AS | Real estate | 2024 |
| Stang Multiservice AS | Construction | 2025 |
| Stansemakeren AS | Manufacturing | 1984 |
| Star Profilering AS | Wholesale & retail | 2005 |
| Stasjonsdrift Andreassen AS | Wholesale & retail | 2019 |
| Statsminister Torpsvei 49 AS | Transport & logistics | 2006 |
| Stordal Autocenter AS | Other services | 1991 |
| Strøm Elektro AS | Construction | 2015 |
| Stubberud Forvaltning AS | | 2026 |
| Surfachem Nordic AS | Wholesale & retail | 2013 |
| Surfellingen 1 Holding AS | Real estate | 2023 |
| Surfellingen Eiendom AS | Real estate | 2010 |
| Systec Solutions AS | Information & communication | 2023 |
| Syver Holding AS | | 2021 |
| Søndre Langsholt Eiendom AS | Real estate | 2018 |
| Søndre Skjeberg Vann- Og Avløpsforetak SA | Water & waste | 2009 |
| Sør-Øst Invest AS | Real estate | 2019 |
| T Norum Invest AS | Real estate | 2005 |
| Tafmof AS | Financial services | 2016 |
| Takstmann Og Byggmester Pedersen AS | Real estate | 2022 |
| Tapa Eiendom AS | Construction | 2008 |
| TC Andersen Transport Ans | Transport & logistics | 1995 |
| Tc.A Holding AS | | 2022 |
| Te Christiansen Holding AS | Other services | 2008 |
| Team Mathias AS | Construction | 2024 |
| Team Pluss Ans | Administrative & support | 2001 |
| Therm AS | Professional & scientific | 2026 |