| Norsk Jernbanesikkerhet AS | Administrative & support | 2015 |
| Norsok-Vedlikehold AS | Construction | 2025 |
| Nål Og Hammer AS | Manufacturing | 2004 |
| Oddmund Thon Holding AS | Real estate | 2012 |
| Okas Butikkutvikling AS | Professional & scientific | 2011 |
| Olsen & Sønn Varmepumpeservice AS | Construction | 2019 |
| Paviljongen Frisør Da | Other services | 1991 |
| PC Hamang Trafikkskole AS | Administrative & support | 2013 |
| Premium Invest AS | Real estate | 2014 |
| PSG Consulting AS | Professional & scientific | 2022 |
| PT by Rødningsby AS | Arts & recreation | 2026 |
| Rammesenteret AS | Wholesale & retail | 1991 |
| Rebo Bygg AS | Construction | 2013 |
| Reef Invest AS | | 1998 |
| Reidar Skogen AS | Construction | 2016 |
| Remi Olsen Holding AS | | 2023 |
| Renmil Service AS | Administrative & support | 2020 |
| Returstål AS | Water & waste | 2013 |
| Revo Entreprenør AS | Construction | 2025 |
| Rostad Byggservice AS | Construction | 2008 |
| Rostad Eiendom AS | Real estate | 2025 |
| S. Rostad Holding AS | | 2021 |
| Sandaker 1930 Holding AS | Administrative & support | 2024 |
| Sandaker 1930 Utleie AS | Administrative & support | 2024 |
| Sarpsborg Byggeservice AS | Construction | 2016 |
| Service 24 AS | Other services | 2013 |
| Service Rørlegger AS | Construction | 2023 |
| SH Montasje AS | Professional & scientific | 2005 |
| Skjeberg Regnskapskontor AS | Professional & scientific | 2005 |
| Skogen R. Eiendom AS | | 2025 |
| Skogen R. Holding AS | | 2025 |
| Slevik Hyttetomter AS | Real estate | 2010 |
| Snekkerteam AS | Construction | 2011 |
| Snekkerteam Blikkenslageravdeling AS | Construction | 2026 |
| Sollmannsvei 2 AS | Real estate | 2016 |
| SRP AS | | 2024 |
| Stabilbygg AS | Construction | 2024 |
| Stensvold Sameie AS | Real estate | 2023 |
| Stensvold Sameie Holding AS | | 2023 |
| Stordahl Holding AS | Real estate | 2005 |
| Sundløkkaveien 8 Eiendom AS | Real estate | 2009 |
| Svullen Vann- Og Avløp SA | Water & waste | 2023 |
| Ta Drift Og Anlegg AS | Construction | 2025 |
| Tak & Renne-Eksperten AS | Administrative & support | 2026 |
| Talgø Tømrerservice AS | Construction | 2018 |
| Team Ungdomsbygg AS | Administrative & support | 2008 |
| Teslow AS | Professional & scientific | 2007 |
| Thomas Eriksen Holding AS | Real estate | 2015 |
| TJ Trefelling AS | Agriculture & fishing | 2013 |
| TKT Eiendom AS | Real estate | 2007 |
| Torodds AS | Information & communication | 2013 |
| Total Fix AS | Professional & scientific | 2025 |
| Vestma Eiendom AS | Real estate | 2018 |
| Vestma Holding AS | Manufacturing | 2018 |
| Vestma Produksjon AS | Manufacturing | 2018 |
| Vestover & Co. AS | Wholesale & retail | 2025 |
| Vollbergveien AS | Real estate | 2022 |
| Youdesign AS | Arts & recreation | 2024 |
| Årvollskogen Barnehage AS | Education | 2011 |
| Østfold Blikkenslagerservice ANS | | 1988 |