| Significance AS | | 2022 |
| Sigo AS | Real estate | 2018 |
| Sigtac AS | Health & social care | 1997 |
| Sigurd Lende AS | | 2021 |
| Sigurd Lende Drift AS | Construction | 2023 |
| Sigurd Syversen AS | Real estate | 2020 |
| Sigurd Vinnes AS | | 2007 |
| Sigurdsen Bygg AS | Construction | 2005 |
| Sigurdsen Invest AS | Real estate | 1997 |
| Sigve Hamre Maskin AS | Construction | 2023 |
| Siira AS | Professional & scientific | 2026 |
| Sija AS | Health & social care | 2023 |
| Silencer AS | Manufacturing | 2015 |
| Sillage AS | Other services | 2025 |
| Silver Mountain AS | Professional & scientific | 2024 |
| Simbell Holding AS | | 2021 |
| Simbo Holding AS | | 2020 |
| Simonsbakken AS | Real estate | 2000 |
| Simonsen & Simonsen Da | Real estate | 2002 |
| Simplex AS | Financial services | 2008 |
| Simply Food AS | Hospitality | 2021 |
| Sina Haven AS | Real estate | 2006 |
| Sindre Bøe Holding AS | Professional & scientific | 2020 |
| Sink Studio AS | Information & communication | 2025 |
| Sinnes Invest AS | | 2024 |
| Sintra Invest AS | | 2021 |
| Sinus Elektro AS | Construction | 2005 |
| Sinus Holding AS | Construction | 2013 |
| Sinus Totalteknisk AS | Professional & scientific | 2020 |
| Sir Solution AS | Professional & scientific | 2005 |
| Sira Invest AS | Real estate | 2017 |
| Sirevåg Sjøgrend AS | Real estate | 2012 |
| Sirkel IT AS | Information & communication | 2020 |
| Sirkulera Miljø AS | Water & waste | 2012 |
| Sis Consulting AS | Health & social care | 2009 |
| Sisbiz AS | | 2021 |
| Siso Holding AS | | 2007 |
| Sissel Lindal Holding AS | Real estate | 2023 |
| Sisuindustry AS | Administrative & support | 2024 |
| Siv.Ing. Torgeir Viddal AS | Professional & scientific | 2016 |
| Sivertsen Holding AS | Financial services | 2005 |
| Sivilarkitekt Leif Larsen Holding AS | Professional & scientific | 2005 |
| Sivilarkitekt Mnal Leif Larsen AS | Professional & scientific | 1998 |
| Siviling. E. Hagen AS | Professional & scientific | 2021 |
| Sivilingeniør Eiliv Skomedal AS | Professional & scientific | 2016 |
| Sivilingeniør Rodvelt AS | Professional & scientific | 1988 |
| Siviløkonom Per a Ousdal AS | | 1991 |
| Sivos AS | Professional & scientific | 2019 |
| Sivtek AS | Professional & scientific | 2005 |
| Sixbynine AS | Information & communication | 2013 |
| SJ Holding & Invest AS | | 2025 |
| Sjac Invest AS | | 2021 |
| Sjo Fasting AS | Professional & scientific | 1993 |
| Sjøkurs AS | Professional & scientific | 2012 |
| SK Dressage AS | Agriculture & fishing | 2025 |
| SK Smartbygg AS | Construction | 2010 |
| Skaar Media AS | Professional & scientific | 2023 |
| Skaarland & Vasvik Entreprenør AS | Construction | 2018 |
| Skaarland & Vasvik Invest AS | Real estate | 2020 |
| Skaarland Invest AS | Real estate | 2001 |
| Skaarlia Barnehage SA | Education | 1997 |
| Skaarlia Eiendomsinvest AS | Real estate | 1999 |
| Skadberg Utvikling AS | Real estate | 2021 |
| Skadberg-Borg Ans | Wholesale & retail | 2010 |
| Skadbergbakken 48 AS | Real estate | 2022 |
| Skadsheim Eiendom AS | Real estate | 2025 |
| Skagen 6 AS | Real estate | 1939 |
| Skagen Bygg AS | Construction | 2014 |
| Skagen Eiendomsdrift AS | Administrative & support | 2016 |
| Skai Holding AS | | 2023 |
| Skarp Reklamebyrå AS | Professional & scientific | 2002 |
| Skarpnes Rør AS | Manufacturing | 1992 |
| Skau Gulv AS | Wholesale & retail | 1990 |
| Skaulen AS | Wholesale & retail | 2005 |
| Skavanken AS | | 2024 |
| Skeggs Invest AS | | 2025 |
| Skei Eiendom AS | Real estate | 1997 |
| Skei Parken Eiendom AS | Financial services | 2005 |
| Skeiane Legesenter AS | Health & social care | 2014 |
| Skeiane Tannlegesenter AS | Health & social care | 2023 |
| Skilltech Nordic SA | Professional & scientific | 2016 |
| Skilthuset AS | Professional & scientific | 1989 |
| Skin Illusion AS | Other services | 2023 |
| Skinvital AS | Other services | 2017 |
| Skippergata 123 AS | Real estate | 2023 |
| Skjervik Holding AS | Real estate | 2014 |
| Skjæreteknikk AS | Manufacturing | 2007 |
| Skjæveland AS | Professional & scientific | 1998 |
| Skjæveland Eiendom Holding AS | Real estate | 2021 |
| Skjæveland Energiteknikk AS | Professional & scientific | 2026 |
| Skjæveland Gruppen AS | Manufacturing | 1987 |
| Skjæveland Gruppen Holding AS | Manufacturing | 2019 |
| Skjæveland Investering AS | Agriculture & fishing | 2005 |
| Skjørestad Gård AS | Wholesale & retail | 2023 |
| SKK Holding AS | Health & social care | 2011 |
| Sklls AS | Professional & scientific | 2017 |
| Skogland Eiendom AS | Real estate | 2020 |
| Skogs Invest AS | Financial services | 2006 |
| Skogsprett AS | Arts & recreation | 2016 |
| Skoleboka Muligheter AS | Information & communication | 2016 |