| Solvika Holding AS | | 2025 |
| Sommerfryd Holding AS | Wholesale & retail | 2022 |
| Sommerfryden AS | Professional & scientific | 1994 |
| Sondre Døli Holding AS | Real estate | 2013 |
| Sortedal & Dahle Holding AS | Construction | 2005 |
| Sortedal Og Dahle Eiendom AS | Real estate | 2007 |
| Soulmama AS | Education | 2025 |
| Spacetime Consulting AS | Professional & scientific | 2021 |
| Sparkling Dreams AS | Wholesale & retail | 2020 |
| Spearmint Invest AS | Financial services | 2010 |
| Specc AS | Information & communication | 2022 |
| Spedisjonshuset AS | Transport & logistics | 2001 |
| Spekter AS | Professional & scientific | 1988 |
| Spekter Reklame AS | Professional & scientific | 2006 |
| SPF Holding AS | Real estate | 2009 |
| SPH Eiendom AS | | 2018 |
| Spilleriet Skien AS | Arts & recreation | 2022 |
| Spillorama Skien AS | Arts & recreation | 1996 |
| Spirdal Holding AS | | 2025 |
| Sport 1 Skien AS | Wholesale & retail | 2011 |
| Sportech AS | Wholesale & retail | 2015 |
| Sportsconsult AS | Health & social care | 2023 |
| Spot AS | Construction | 2018 |
| Spot Engineering AS | Professional & scientific | 2024 |
| Squash Senteret Ans | Wholesale & retail | 1991 |
| Sras AS | Professional & scientific | 2005 |
| SRB AS | Construction | 2021 |
| SRB Holding AS | Construction | 2021 |
| SRX Logistikk AS | Transport & logistics | 2026 |
| Ssø Holding AS | | 2023 |
| Staahlen Kulde Og Varme AS | Construction | 2025 |
| Stadionbygg AS | Real estate | 1997 |
| Stage AS | Administrative & support | 2017 |
| Stage Backline AS | Wholesale & retail | 2006 |
| Stallmannsvingen 1 AS | Real estate | 2023 |
| Stamland Betongentreprenør AS | Construction | 2025 |
| Star Bil AS | Wholesale & retail | 2010 |
| Star Bilskade Vestfold Og Telemark AS | Other services | 1991 |
| Starks AS | Wholesale & retail | 2016 |
| Starlease AS | Administrative & support | 2019 |
| Stasjonsdrift Skien AS | Wholesale & retail | 2002 |
| Stasjonsvegen 1 Bø AS | Real estate | 2016 |
| Stathelle Terminalen AS | Real estate | 1983 |
| Stavdal Eiendom AS | Real estate | 2008 |
| Stavdal Maskin AS | Construction | 2021 |
| Stavdal Vannverk SA | Water & waste | 1949 |
| Stavnem & Aasen AS | Real estate | 2021 |
| Stavnem Invest AS | | 2020 |
| STB Solar AS | Construction | 2023 |
| Sted Arkitektur AS | Professional & scientific | 2018 |
| Steen-Hansen & Skuggedal AS | Construction | 2025 |
| Steen-Hansen Maskin AS | Construction | 2007 |
| Steff AS | Professional & scientific | 2024 |
| Steff Eiendom AS | Real estate | 2021 |
| Steinar Moe Eiendom AS | Real estate | 1979 |
| Steinde AS | Professional & scientific | 2005 |
| Steinde Environmental AS | Professional & scientific | 2020 |
| Steinhaug Eiendom AS | Manufacturing | 2014 |
| Steinrove AS | Administrative & support | 2025 |
| Sten Åge Egeberg Engineering AS | Professional & scientific | 2024 |
| Stenge AS | | 2019 |
| Stensrud Maskin Og Montasje AS | Construction | 2025 |
| Stensrud Mek. AS | Other services | 2020 |
| Stensrud Multiservice AS | Construction | 2025 |
| Stensrud Truck Eiendom AS | Real estate | 2011 |
| Stensrød Maskin Skog Og Jordbruk AS | Construction | 2023 |
| Stensrød Takst Og Byggvurdering AS | Professional & scientific | 2026 |
| Stensvold AS | Wholesale & retail | 1998 |
| Stercus AS | Real estate | 2026 |
| Sterner & Stalsberg Laserservice AS | Administrative & support | 2024 |
| STH Data AS | Wholesale & retail | 1988 |
| Sti Gård Da | Agriculture & fishing | 2025 |
| Stiann Holding AS | | 2023 |
| Stitho Holding AS | Wholesale & retail | 2022 |
| Stock Supply AS | Wholesale & retail | 2011 |
| Stoke Invest AS | Financial services | 2016 |
| Store Blå AS | Real estate | 2012 |
| Store Mæla Gård Antik Da | Wholesale & retail | 2014 |
| Storemyr Beitelag SA | Agriculture & fishing | 1995 |
| Storgata 87 AS | Real estate | 2020 |
| Storkjøkken Telemark AS | Other services | 2023 |
| Stormax Holding AS | Administrative & support | 2007 |
| Storrun Invest AS | Real estate | 2003 |
| Strai Kjøkken Skien AS | Wholesale & retail | 2013 |
| Strander Eiendom AS | Real estate | 1987 |
| Strandveien 6 AS | Real estate | 2008 |
| Strikkepinnen Skien AS | Wholesale & retail | 2010 |
| Stripe Media AS | Professional & scientific | 2019 |
| Strøm Mat & Bar AS | Hospitality | 2013 |
| Strøm Mat & Bar Holding AS | Hospitality | 2013 |
| Strøm Sivertsen AS | Construction | 1997 |
| Strøm Sivertsen Eiendom AS | Construction | 2016 |
| Strøm Sivertsen Holding AS | Construction | 2016 |
| Strømbygg AS | Construction | 2024 |
| Strømdal Eiendom AS | Real estate | 2017 |
| Strømdal Utvikling AS | Real estate | 2025 |
| Strømdaljordet Invest AS | Real estate | 2022 |
| Strømtangveien Eiendom AS | | 2014 |
| STS Transport AS | Transport & logistics | 2000 |
| Studio Marichen Nuf | Other services | 2007 |