| Strømmen Båt & Bil AS | Real estate | 2005 |
| Strømmen Hills AS | Real estate | 2023 |
| Strømsbu AS | Real estate | 2017 |
| Strømsbu Torg AS | Real estate | 2021 |
| Strømsbugården AS | Real estate | 2004 |
| Strømsbusletta 9 AS | Real estate | 2004 |
| Strømsbuveien 42 AS | Real estate | 2002 |
| Strømsbuåsen Garasjelag 2 SA | Real estate | 1963 |
| Strømsland Holding AS | Wholesale & retail | 2023 |
| STS - Surface Treatment Systems AS | Wholesale & retail | 1981 |
| Studio 5 Arendal AS | Other services | 2022 |
| Studio Albertine AS | Wholesale & retail | 1987 |
| Studio M Stoa AS | Other services | 2013 |
| Studio One AS | Wholesale & retail | 2006 |
| Studiocapelli Frisør AS | Other services | 2018 |
| Ståle Sørbøe AS | | 2019 |
| Stærk & Co AS | Professional & scientific | 2018 |
| Stølsvigen Dental AS | Health & social care | 2022 |
| Sub 1 AS | Hospitality | 2007 |
| Sub 11 AS | Hospitality | 2016 |
| Sub 4 AS | Hospitality | 2020 |
| Sub 5 AS | Hospitality | 2020 |
| Sub 6 AS | Hospitality | 2020 |
| Sub 7 AS | Hospitality | 2020 |
| Sub 8 AS | Hospitality | 2020 |
| Sub Farmandstredet AS | Administrative & support | 2011 |
| Sub Holding AS | Hospitality | 2019 |
| Sub Norge AS | Administrative & support | 2011 |
| Sub Trondheim AS | Hospitality | 2018 |
| Subeco AS | Wholesale & retail | 2021 |
| Sukkerfrittliv AS | Wholesale & retail | 2024 |
| Sunbird AS | | 2021 |
| Suncat Invest AS | Wholesale & retail | 2005 |
| Sundberg Helse AS | Health & social care | 2017 |
| Sunnsoft Publishing AS | Information & communication | 2013 |
| Surfnet AS | Information & communication | 2022 |
| Surfnet Mdu AS | Information & communication | 2025 |
| Svalestien Barnehage AS | Education | 2007 |
| Sven a Andersen AS | Construction | 2021 |
| Svenn Nystrand Bygg AS | Construction | 2025 |
| Svøm Og Redning AS | Education | 2024 |
| Syd-Vest Holding AS | Health & social care | 2017 |
| Sykkelsport AS | Wholesale & retail | 2000 |
| Syklusentusiasten AS | Education | 2022 |
| Symposium Restaurant AS | Hospitality | 2012 |
| Syrdalen & Roscher Ans | Real estate | 1986 |
| Strømsbusletta 11 A/S | Real estate | 1988 |
| Surface Consultation AS | Professional & scientific | 1988 |
| Sødal Holding AS | Health & social care | 2019 |
| Søgaard Eiendom AS | Real estate | 2020 |
| Søndenå Holding AS | | 2023 |
| Sør Budbil Service AS | Transport & logistics | 2014 |
| Sør Eiendomsinvest AS | Real estate | 2021 |
| Sør Forsikring AS | Financial services | 2006 |
| Sør Pharma Invest AS | | 2020 |
| Sør Regnskap Ans | Professional & scientific | 2003 |
| Sør Spedisjon AS | Transport & logistics | 1992 |
| Sør Stangebye Reklamebyrå AS | Professional & scientific | 2008 |
| Sør Økonomi AS | Administrative & support | 2003 |
| Sør-Eiendom Og Drift AS | | 2025 |
| Sørco Eiendom AS | Real estate | 2018 |
| Sørco Eiendomsutvikling AS | Real estate | 2019 |
| Sørco Holding AS | Real estate | 2018 |
| Sørco Invest AS | Real estate | 1975 |
| Sørco Kjøpesenter AS | Real estate | 2016 |
| Sørco Nedenes 1 AS | Real estate | 1975 |
| Sørco Nedenes 2 AS | Real estate | 2014 |
| Sørco Utvikling Og Drift AS | Real estate | 2014 |
| Sørdykk AS | Wholesale & retail | 2019 |
| Sørensen & Moen Bygg AS | Construction | 2011 |
| Sørensen & Moen Invest AS | Construction | 2024 |
| Sørhus Bygg AS | Construction | 2025 |
| Sørlandet Auto AS | Wholesale & retail | 2020 |
| Sørlandet Bil AS | Wholesale & retail | 2017 |
| Sørlandet Bruktbil AS | Wholesale & retail | 2015 |
| Sørlandet Brønnboring AS | Construction | 1994 |
| Sørlandet Fixit AS | Manufacturing | 2017 |
| Sørlandet Rekruttering AS | Administrative & support | 2017 |
| Sørlands-Tjenesten AS | Construction | 2025 |
| Sørlandshus Arendal Ans | Construction | 1996 |
| Sørlandskjøkken Arendal AS | Wholesale & retail | 2022 |
| Sørlandsklinikken Øre Nese Hals | Health & social care | 2007 |
| Sørlie Eiendom AS | Real estate | 2003 |
| Sørsvannsveien 1 AS | Real estate | 2005 |
| Søsknene Grova Da | Agriculture & fishing | 1973 |
| Søstrene Kjevik AS | Health & social care | 2023 |
| T & U Logistikk AS | Transport & logistics | 2021 |
| T Bergtun Eiendom AS | Real estate | 1999 |
| T Og T AS | Professional & scientific | 2024 |
| T P Auto AS | Wholesale & retail | 2023 |
| T P Shipping AS | Transport & logistics | 1986 |
| T.K Holding AS | | 2021 |
| T.L Holding AS | | 2025 |
| T.R.J. Holding AS | | 2005 |
| Tabi Nexus AS | Administrative & support | 2025 |
| Tagbox AS | Information & communication | 2017 |
| Tago AS | Real estate | 1988 |
| Takst & Mesterbygg AS | Professional & scientific | 2023 |
| Tang & Jacobsen AS | Administrative & support | 2007 |
| Tangen Alle 41 AS | Real estate | 2021 |