| Sivana AS | | 2026 |
| Sivi Bygg Da | Construction | 2002 |
| SJ Invest AS | Wholesale & retail | 1995 |
| Sjøgaten En AS | Arts & recreation | 1995 |
| Skaala Ugland & Nielsen AS | Real estate | 2015 |
| Skaarstein Da | Information & communication | 2015 |
| Skagerrak Offshore AS | Professional & scientific | 2022 |
| Skalleberg Drift AS | Administrative & support | 2019 |
| Skandinavisk Førstehjelp AS | Health & social care | 2013 |
| Skarpnes AS | Manufacturing | 2012 |
| Skarpnes Holding AS | Manufacturing | 2016 |
| Skibåsen 9A AS | Real estate | 2021 |
| Skiftenes Sag Ans | Manufacturing | 1989 |
| Skjold Pro AS | Wholesale & retail | 2026 |
| Skjærgårdstannlegene Da | Health & social care | 2009 |
| Skolegaten 2 AS | Real estate | 2023 |
| Skolegaten 3 AS | Real estate | 2023 |
| Skorstad AS | | 2025 |
| Skotta Eiendom AS | Real estate | 2023 |
| Skram Holding AS | | 2025 |
| Sky Fitness Grimstad AS | Arts & recreation | 2019 |
| Smag & Behag AS | Hospitality | 2011 |
| Smak Av Asia Grimstad AS | Wholesale & retail | 2015 |
| Smaken Av Grimstad AS | Manufacturing | 2011 |
| Smart Ocean AS | Professional & scientific | 2016 |
| Smaue AS | Hospitality | 2014 |
| Smite AS | Professional & scientific | 2014 |
| Smith Petersens Gate 7 AS | Real estate | 2007 |
| Smith Petersens GT. 4 AS | Real estate | 2011 |
| SMR Invest AS | Real estate | 2022 |
| Smårolling AS | Wholesale & retail | 2026 |
| Snar 2 Da | Agriculture & fishing | 2023 |
| Snefrids Hus Ltd Nuf | Wholesale & retail | 2009 |
| So Cars AS | Wholesale & retail | 2021 |
| Socialdock AS | Information & communication | 2025 |
| SOLAR4SEA AS | Professional & scientific | 2026 |
| Solberg Regnskap AS | Professional & scientific | 2023 |
| Solfrid Koanda WL AS | Education | 2024 |
| Solid Plan AS | Professional & scientific | 2017 |
| Solid Trening Og Helse AS | Arts & recreation | 2023 |
| Solli Invest AS | Financial services | 1989 |
| Solodd Event AS | Arts & recreation | 2003 |
| Soloddveien AS | Real estate | 2010 |
| Soltoppen Grimstad AS | Information & communication | 2022 |
| Solventor AS | Professional & scientific | 2026 |
| Solås Bygdeservice AS | Construction | 2026 |
| Soma Red Light AS | Wholesale & retail | 2024 |
| Sondre Larsen AS | Transport & logistics | 2022 |
| Spencer Consulting AS | Professional & scientific | 2021 |
| Sperre Gulvsliping AS | Construction | 2015 |
| Spinnerigården AS | Manufacturing | 1998 |
| Sporten Grimstad AS | Wholesale & retail | 2018 |
| SPV Heroes AS | | 2023 |
| Spyleservice Sør AS | Construction | 2026 |
| SR Eiendom Sør AS | Real estate | 2017 |
| Stafa Industrier AS | Wholesale & retail | 1985 |
| Stalleland AS | Professional & scientific | 2020 |
| Stalleland Invest AS | Administrative & support | 2005 |
| Star Asia Da | Wholesale & retail | 2006 |
| Steinekspert Og Utemiljø AS | Construction | 2023 |
| Steinlegger Steinli AS | Administrative & support | 2024 |
| Steinmoen - Din Reklamepartner AS | Professional & scientific | 2002 |
| Stenderbygg AS | Construction | 2020 |
| Stenevik Hav AS | Professional & scientific | 2023 |
| Stensvand Eiendom AS | Real estate | 2016 |
| STG14 AS | Real estate | 2024 |
| Stie Invest AS | | 2021 |
| Sties Termo-Transport AS | Arts & recreation | 2022 |
| Stili Invest AS | Real estate | 2002 |
| Stine Sofies Eiendom AS | Real estate | 2015 |
| Stockastic AS | | 2025 |
| Storgada 23 AS | Real estate | 2005 |
| Storgada 40 AS | Information & communication | 2011 |
| Storgata 20 Grimstad AS | Real estate | 2011 |
| Storgata 46B AS | Real estate | 2013 |
| Storgaten 20 Lillesand AS | Real estate | 2007 |
| Storgaten 28 Grimstad AS | Real estate | 2015 |
| Storgaten 33 Grimstad AS | Real estate | 2023 |
| Storgaten 37-39 AS | Real estate | 2017 |
| Storgt 11 Grimstad AS | Real estate | 2013 |
| Storgt 12 Grimstad AS | Real estate | 2013 |
| Storgt 18 Grimstad AS | Real estate | 2013 |
| Strandfjorden Eiendom AS | Real estate | 1997 |
| Stranna AS | Professional & scientific | 2006 |
| Stripo Sør AS | Real estate | 2024 |
| Strøm & Sånn AS | Construction | 2023 |
| Strømsbu Hage AS | Real estate | 2015 |
| Studio Design AS | Professional & scientific | 2021 |
| Studio Hoelfeldt Lund AS | Professional & scientific | 2019 |
| Studio Mano AS | Other services | 2025 |
| Studio S Hudklinikk AS | Other services | 2022 |
| Stumtjener AS | Information & communication | 2020 |
| Styrke&Mestring Med Eirin AS | Education | 2025 |
| Støleveien 170 AS | Real estate | 2013 |
| Støleveien AS | Real estate | 2019 |
| Subsea Robotics AS | Professional & scientific | 2022 |
| Sundveien Rønnes Samvirkeforetak | Real estate | 1977 |
| Svemi AS | | 2018 |
| Svennings Bygg AS | Construction | 2018 |
| Sverre's Multiservice AS | Transport & logistics | 2026 |