| Skien Trafikkskole Da | Education | 1994 |
| Skien Varmesenter AS | Wholesale & retail | 2008 |
| Skien Vekst AS | Real estate | 1972 |
| Skien Veterinærklinikk AS | Professional & scientific | 2024 |
| Skien Øyelegesenter AS | Health & social care | 2023 |
| Skiendecor AS | Arts & recreation | 2025 |
| Skiens Aktiebakeri | Manufacturing | 1963 |
| Skiens Automobilverksted AS | Other services | 2002 |
| Skiens Cykkelfabrik AS | Manufacturing | 2017 |
| Skiens Persiennefabrikk AS | Manufacturing | 2023 |
| Skiens Rustfri Industri AS | Manufacturing | 2005 |
| Skilbred AS | Wholesale & retail | 2008 |
| Skiltmaker Haugen AS | Professional & scientific | 1987 |
| Skin-Tex AS | Wholesale & retail | 1995 |
| Skippergata 14 AS | Real estate | 2019 |
| Skippergata 4 AS | Real estate | 2017 |
| Skippergata 8 AS | Real estate | 2022 |
| Skippergata Bygg AS | Real estate | 2015 |
| Skistredet 7 AS | Real estate | 1994 |
| Skistrædet Invest AS | Professional & scientific | 2007 |
| Skjelbred Utleie AS | Real estate | 2023 |
| Skog Og Anleggstjenester AS | Agriculture & fishing | 2023 |
| Skogenergi Varme AS | Energy | 2007 |
| Skogmusa Barnehage SA | Education | 1991 |
| Skogsbilveglaget Tollefsrudsetervegen SA | Real estate | 1933 |
| Skoies AS | Wholesale & retail | 2020 |
| Skolemiljø-Barnehagemiljø AS | Education | 2023 |
| Skotfoss Brug AS | Real estate | 2005 |
| Skotfoss Bruk Da | Real estate | 2000 |
| Skotfoss Engineering and Technology AS | Wholesale & retail | 2020 |
| Skotfossveien 35 AS | Real estate | 2017 |
| Skreppestad Eiendom AS | Real estate | 2005 |
| Skui Takst AS | Real estate | 2025 |
| Skupa AS | Administrative & support | 2021 |
| Skuring AS | Professional & scientific | 2020 |
| Skyer Maskin AS | Construction | 2011 |
| Skyview AS | Professional & scientific | 2026 |
| Skårdal Andersen Invest AS | | 2026 |
| SL Drive AS | Transport & logistics | 2024 |
| Sle Invest AS | Professional & scientific | 2019 |
| Slemdalsgate 2 AS | Real estate | 2005 |
| Sletholts AS | Construction | 1986 |
| Slipt Betong AS | Construction | 2017 |
| SLL Holding AS | | 2022 |
| Slottsbrugata 35 AS | Real estate | 2021 |
| Slåen AS | Wholesale & retail | 2023 |
| Slåttedalen Holding AS | Financial services | 2015 |
| SM Solar Solutions AS | Construction | 2024 |
| Smart and Safe AS | Information & communication | 2026 |
| Smart-Bygg AS | Construction | 2021 |
| SMB Consult AS | Professional & scientific | 2003 |
| Sme Omsorgsboliger AS | Real estate | 2025 |
| Smedgata 33 AS | Real estate | 2019 |
| Smga Antikk & Auksjon AS | Wholesale & retail | 2023 |
| SMS Omsorg AS | Health & social care | 2014 |
| Sms-Holding AS | Administrative & support | 2015 |
| Smådyrkrematoriet AS | Agriculture & fishing | 1997 |
| Småtjenester App AS | Information & communication | 2015 |
| Smøregrava Holding AS | | 2022 |
| Snekker Og Tømrer Gutta AS | Construction | 2024 |
| Snekkerhammer'N Ltd Nuf | Construction | 2005 |
| Snekkermester Høvelflis Invest AS | Real estate | 2016 |
| Snekkerservice Grenland AS | Construction | 2012 |
| Snipetorp 2 Og 4 AS | Real estate | 2019 |
| Snipetorp Eiendom Da | Real estate | 2001 |
| Snipetorpgata 13B AS | Real estate | 2018 |
| Snipetorpgata 30 & 39 AS | Real estate | 2024 |
| Snipetorpgata AS | Real estate | 2018 |
| Snowball Digital AS | Information & communication | 2016 |
| Snupp Holding AS | Financial services | 2008 |
| Snupp Holding II AS | | 2026 |
| SNW Invest AS | | 2024 |
| Sofitian AS | Wholesale & retail | 2018 |
| Soilvation AS | Professional & scientific | 2025 |
| Sol Eiendomsutvikling AS | Real estate | 2022 |
| Solaas Utvikling AS | Real estate | 2008 |
| Solbakk Rådgjeving AS | Transport & logistics | 2023 |
| Solbakken Eiendomssalg AS | Real estate | 2017 |
| Solbakkens Holding AS | Real estate | 2022 |
| Solbekk Invest AS | Financial services | 2007 |
| Solberg Bil AS | Wholesale & retail | 1975 |
| Solberg Eiendom Og Utleie AS | Real estate | 2016 |
| Solcelle Og Energisenteret AS | Construction | 2022 |
| Solgun Holding AS | Financial services | 2018 |
| Solheim Gård Utleieservise AS | Administrative & support | 2025 |
| Solheimhus AS | Professional & scientific | 1965 |
| Soli Holding AS | | 2024 |
| Solid Multibygg AS | Construction | 2025 |
| Solid Solutions Da | Information & communication | 2026 |
| Solli Services AS | Professional & scientific | 2020 |
| Sollid Trafikkskole AS | Education | 2015 |
| Sollis Sporthorses AS | Agriculture & fishing | 2026 |
| Solsikken Vekst AS | Health & social care | 2008 |
| Solstad Bunadsverksted AS | Wholesale & retail | 2025 |
| Soltoppen Invest AS | Administrative & support | 2017 |
| Soltys Holding AS | Hospitality | 2024 |
| Solum Fysioterapi Og Akupunktur Da | Health & social care | 2008 |
| Solumlege AS | Health & social care | 2026 |
| Solutiofm Consult AS | Professional & scientific | 2024 |
| Solvika Campingsenter AS | Hospitality | 2020 |