| Shaina AS | Professional & scientific | 2020 |
| Shakes & Burgers AS | Hospitality | 2020 |
| Shampoo AS | Wholesale & retail | 2017 |
| Shape Services AS | Professional & scientific | 1999 |
| Shaw AS | Real estate | 2015 |
| She AS | Education | 2018 |
| Shelf Sigma AS | | 2026 |
| Shelf Ypsilon AS | | 2026 |
| Shenanigans Da | Arts & recreation | 2004 |
| Shero Barber King AS | Other services | 2024 |
| Shetland AS | Professional & scientific | 2025 |
| Shinywings AS | Administrative & support | 2017 |
| SHL Invest AS | | 2023 |
| Shox Consulting AS | Professional & scientific | 2021 |
| Shrimpvision AS | Agriculture & fishing | 2019 |
| Shtix AS | Wholesale & retail | 2025 |
| Shyer AS | Information & communication | 2021 |
| Shyer Holding AS | Information & communication | 2021 |
| Siamratree AS | Hospitality | 2015 |
| Sibama Holding AS | Financial services | 2014 |
| Sibo Invest AS | | 2018 |
| Sibus Import AS | Wholesale & retail | 2022 |
| Sici AS | Professional & scientific | 2015 |
| Side Brok Da | Arts & recreation | 2004 |
| Siderbardrift AS | Hospitality | 2025 |
| Siffer AS | Professional & scientific | 2005 |
| Siga Invest AS | Real estate | 2013 |
| Sigdestad Kraftverk AS | Energy | 2016 |
| Sigmund Stenersen AS | | 2024 |
| Sign Reklame AS | Professional & scientific | 2006 |
| Signalen Invest AS | Real estate | 2010 |
| Signals AS | Information & communication | 2016 |
| Signatur Psykologtjenester AS | Education | 2026 |
| Signe Bergvoll Språktenester AS | Professional & scientific | 2020 |
| Signo Dokken AS | Health & social care | 1993 |
| Sigurd Elholm Barber-Frisør AS | Other services | 2007 |
| Sigurd Eriksens Eftf. AS | Wholesale & retail | 2025 |
| Sigurdson AS | Administrative & support | 2016 |
| Sijoni Invest AS | Professional & scientific | 2007 |
| Sikthaugen AS | Real estate | 2023 |
| Sildinvest AS | Real estate | 1934 |
| Silje Hindenes AS | | 2023 |
| Silje Stenersen Holding AS | | 2025 |
| Silk & Style Da | Wholesale & retail | 1996 |
| Silmaril Invest AS | | 2023 |
| Silver Ice AS | Transport & logistics | 2019 |
| Silver Liner AS | Transport & logistics | 2009 |
| Silver Liner Faroe | | 2020 |
| Silver Liner Holding AS | Transport & logistics | 2018 |
| Silver Lining IT AS | Information & communication | 2017 |
| Silver Sea AS | Transport & logistics | 2010 |
| Silver Sea TC AS | Transport & logistics | 2010 |
| Silver Supporter AS | Transport & logistics | 2018 |
| Silver-Holding AS | Transport & logistics | 2005 |
| Silver-Invest AS | Transport & logistics | 2005 |
| Silverfox Holding AS | Financial services | 2016 |
| Simbad AS | | 2026 |
| Simen Ormberg Holding AS | Financial services | 2021 |
| Simi AS | Real estate | 1998 |
| Simon Aasen Holding AS | | 2019 |
| Simonnæs Admin AS | Professional & scientific | 2021 |
| Simonnæs Eiendom I AS | Real estate | 2022 |
| Simonnæs Eiendom II AS | Real estate | 2022 |
| Simonnæs Eiendom III AS | Real estate | 2022 |
| Simonnæs Holding AS | Real estate | 2003 |
| Simonnæs Kapital AS | Information & communication | 2022 |
| Simonnæs Miljø AS | Real estate | 2022 |
| Simonnæs Servering AS | Hospitality | 1995 |
| Simonnæsgården AS | Real estate | 1972 |
| Simonsviken Næringspark AS | Real estate | 2008 |
| Simplify AS | | 2005 |
| Simpson Spence Young Norway AS | Transport & logistics | 2026 |
| Simula Uib AS | Professional & scientific | 2015 |
| Sina Konsult AS | Professional & scientific | 2015 |
| Sindre Møgster Braaten Holding AS | | 2023 |
| Singelstad Holding AS | Financial services | 2014 |
| Single Malt Dreams AS | Wholesale & retail | 2021 |
| Singularity Capital AS | Financial services | 2016 |
| Sinow Medical AS | Information & communication | 2019 |
| Sinus Frontalis AS | Health & social care | 2017 |
| Sinys AS | | 2023 |
| Sinø Holding AS | Real estate | 2006 |
| Sirius AS | Real estate | 1997 |
| Sirius Eiendom AS | Real estate | 1995 |
| Sirius Forvaltning AS | Real estate | 1999 |
| Sirkeltomten II AS | Real estate | 1999 |
| Sisae AS | | 2021 |
| Sisyphus Holding AS | | 2023 |
| Sitem AS | Professional & scientific | 2005 |
| Sitetwin AS | Information & communication | 2025 |
| Sivertsen & Co AS | | 2011 |
| Sivilingeniør Helge Hopen AS | Professional & scientific | 2005 |
| Sivilingeniør Petter Kloster AS | Professional & scientific | 2004 |
| Sivilingeniør Robert Storbekk AS | Wholesale & retail | 2003 |
| Sivlesgate 14 AS | Households | 1956 |
| Sivwas AS | Real estate | 1991 |
| Sjaaholm Knudsen AS | Professional & scientific | 2012 |
| Sjaak Holding AS | | 2024 |
| Sjasminte AS | Professional & scientific | 2021 |
| Sjel AS | Real estate | 2025 |