| Scan Trade AS | Wholesale & retail | 2001 |
| Scan Trade Holding AS | Wholesale & retail | 2003 |
| Scandinavian Construction Group AS | Administrative & support | 2021 |
| Scandinavian Twist AS | Wholesale & retail | 2021 |
| Schie Invest AS | | 2019 |
| Schindler AS | Manufacturing | 1977 |
| Seco AS | Wholesale & retail | 2023 |
| Semyang AS | Wholesale & retail | 2023 |
| Sentrum Jern Og Farge Drift AS | Wholesale & retail | 2008 |
| Sentrum Jern Og Farge Eiendom Da | Real estate | 1999 |
| Sentrum Treningssenter AS | Arts & recreation | 1999 |
| SERVER24 AS | Information & communication | 2008 |
| Service AS | Manufacturing | 1954 |
| Servicekompaniet AS | Administrative & support | 2020 |
| Siste Spiker AS | Construction | 2016 |
| SK Bygg & Betong AS | Construction | 2023 |
| Skansengården AS | Real estate | 2013 |
| Skansenklinikken AS | Health & social care | 2016 |
| Sketchboard AS | Financial services | 2005 |
| Skien Lekeland AS | | 2026 |
| Skiltspesialisten AS | Manufacturing | 1997 |
| Skippergata 93 AS | Real estate | 2025 |
| Skjærli Maskin AS | Construction | 2024 |
| Skjærli Mur AS | Construction | 2023 |
| Skårdal AS | Real estate | 2016 |
| Slotten Holding AS | | 2025 |
| Smart Hjem AS | Real estate | 2024 |
| Smartteam Nuf | Information & communication | 2007 |
| SNB Eiendom AS | Real estate | 2025 |
| Sne Eiendomsutvikling AS | Real estate | 2012 |
| Snømyra Barnehage SA | Education | 1991 |
| Snørydding Kjell Tore Hagen AS | Administrative & support | 2014 |
| Socialyou AS | Professional & scientific | 2018 |
| Soka AS | Wholesale & retail | 2023 |
| Som I Byen AS | | 2022 |
| Sona Holding AS | Health & social care | 2021 |
| Sopitas Thaimat AS | Hospitality | 2022 |
| Sordal Bygg AS | Construction | 2011 |
| Sordal Holding AS | Construction | 2012 |
| Sowdiak Er Aller Best AS | Arts & recreation | 2024 |
| Sowdiaks Fall AS | Real estate | 2021 |
| Soyna AS | | 2024 |
| SP Bemanning AS | Information & communication | 2015 |
| SP Tak AS | Construction | 2019 |
| Sport Og Fritid AS | Wholesale & retail | 1991 |
| Sportsgården AS | Real estate | 2000 |
| Stas Holding AS | | 2024 |
| Stasjonsdrift Kannemeyer AS | Wholesale & retail | 2019 |
| Steinsland Invest AS | Real estate | 2021 |
| Steinsland Maskin AS | Construction | 2022 |
| Stemhei 3 AS | Real estate | 2009 |
| Stillas Solutions Vennesla AS | Construction | 2023 |
| Storck Studio AS | Wholesale & retail | 2021 |
| Stormark Holding AS | Real estate | 2025 |
| Stormo AS | Construction | 2000 |
| Straismoen 5-9 AS | Real estate | 2015 |
| Strandberg Og Ingebretsen Malerfirma Da | Construction | 1998 |
| Stratega Productions AS | Information & communication | 1996 |
| Strengtec AS | Construction | 2011 |
| Stubstad AS | | 2024 |
| Stur Services AS | Manufacturing | 2024 |
| Styrevern AS | Real estate | 2024 |
| Støleheia Pukkverk AS | Mining & quarrying | 2006 |
| Svendsen Invest AS | Real estate | 2011 |
| Svendsen Rekruttering, Rådgivning Og Utvikling AS | Administrative & support | 2022 |
| Svendsengruppen AS | Real estate | 2011 |
| Sverre Eikeland AS | Construction | 2012 |
| Syd Holding AS | | 2026 |
| Sør Audio Da | Wholesale & retail | 2008 |
| Sørland Invest AS | Hospitality | 2026 |
| Sørland Regnskap AS | Professional & scientific | 2024 |
| Sørlandet Boligutvikling AS | Real estate | 2025 |
| Sørlands Trykk Og Grafikk AS | Professional & scientific | 2023 |
| Sørlandstjenester AS | Real estate | 2019 |
| Sørporten AS | Professional & scientific | 2020 |
| T. Berntsen Holding AS | Manufacturing | 2022 |
| T. Magnussen Holding AS | Real estate | 2005 |
| Te Bygg AS | Construction | 2017 |
| Team Spirit AS | Health & social care | 2023 |
| Team Ung AS | Administrative & support | 2025 |
| Tej Eiendom AS | Real estate | 2005 |
| Tek International AS | Wholesale & retail | 2023 |
| Teknikken Eiendom Flekkefjord AS | Real estate | 2025 |
| Teologitavla AS | Other services | 2021 |
| Terje Urdal AS | Construction | 2013 |
| Terje Vik Schei AS | Wholesale & retail | 2016 |
| TG Eiendom Sør AS | Real estate | 2022 |
| TGK Bygg & Betong AS | Construction | 2023 |
| TGK Eiendom AS | Real estate | 2025 |
| TH Haus AS | Real estate | 1921 |
| THC Eiendom AS | | 2018 |
| The Bike Corner AS | Wholesale & retail | 2019 |
| The Hairfactory AS | Other services | 2013 |
| THOMASSEN1960 AS | Wholesale & retail | 2006 |
| Thschie Invest AS | | 2023 |
| Thunder Invest AS | Real estate | 2007 |
| Ti-Tech Sveis AS | Manufacturing | 1995 |
| Tid & Syn AS | Wholesale & retail | 1991 |
| Tidløs Gave Og Interiør AS | Wholesale & retail | 2023 |
| Tine Marie Rekve Stein AS | Wholesale & retail | 2022 |