| So-El Holding AS | Construction | 2017 |
| Solfjeld AS | Manufacturing | 1998 |
| Solfjeld Eiendom AS | Manufacturing | 2008 |
| Solgløtt Eiendom AS | | 2008 |
| Solidum Eiendom AS | Real estate | 2023 |
| Songe Bakken AS | Wholesale & retail | 2020 |
| Sportco Tvedestrand AS | Wholesale & retail | 2008 |
| Square One Booking Abrahamsen Kleven Og Helseth Ans | Arts & recreation | 2001 |
| Sta-Fondet AS | Financial services | 2006 |
| Stausland Eiendom AS | Real estate | 2023 |
| Stausland Holding AS | Construction | 2022 |
| Stian Lunde Eiendom AS | Real estate | 2023 |
| Stian Lunde Holding AS | | 2023 |
| Stranna Maritime AS | Wholesale & retail | 2002 |
| Stranna Maritime Eiendom AS | Real estate | 2021 |
| Stranna Maritime Holding AS | Real estate | 2021 |
| Strannasko AS | Wholesale & retail | 2011 |
| Stærk Elektro AS | Construction | 2024 |
| Størdal Gård AS | Hospitality | 2020 |
| Sundsdal Roaldsnes Holding AS | | 2026 |
| Suntec AS | Manufacturing | 2000 |
| Sveum Hagesenter AS | Wholesale & retail | 2022 |
| Svevoe AS | Real estate | 2021 |
| Sølvi Iren AS | Wholesale & retail | 2022 |
| Sønnavind Holding AS | | 2022 |
| Sønnavind Media AS | Professional & scientific | 2022 |
| Sørlands Gruppen AS | | 2008 |
| Sørlandsbrygga AS | Manufacturing | 1998 |
| T Abusdal Holding AS | | 2023 |
| Tahas Eiendom AS | Real estate | 2014 |
| Tahtec AS | Professional & scientific | 2022 |
| Takstmann Morten H Storm AS | Real estate | 2017 |
| Tangenbukta AS | Manufacturing | 1979 |
| Tangenheia Utvikling AS | Real estate | 2022 |
| Teamtec AS | Manufacturing | 1995 |
| Teamtec Waste to Energy AS | Professional & scientific | 2015 |
| Tekagain AS | Wholesale & retail | 2026 |
| Tekstil Sør AS | Wholesale & retail | 2022 |
| Teloks AS | Manufacturing | 1987 |
| Tenk-Eiendom AS | Real estate | 2015 |
| Terje Jakobsen Holding AS | Manufacturing | 2025 |
| Tewo Industrier AS | Manufacturing | 2025 |
| Thor Hartvig Lunde AS | Construction | 2025 |
| Thorbjørnsens Kjøreskole AS | Education | 1998 |
| Tjennaparken AS | Real estate | 2015 |
| TM Bygg AS | Construction | 2021 |
| Tor Arne Hauge AS | Real estate | 2005 |
| Tor Med Hammeren AS | Construction | 2010 |
| Tore Olsen Salg AS | Manufacturing | 1988 |
| Torridalsveien 50 AS | Real estate | 2025 |
| Total Vekst AS | Administrative & support | 2014 |
| TT Investments AS | | 2024 |
| Tvedefjord AS | Hospitality | 2016 |
| Tvedestrand Bakeri AS | Manufacturing | 2017 |
| Tvedestrand Blikkenslagerverksted AS | Construction | 1999 |
| Tvedestrand Boligutvikling AS | Real estate | 2023 |
| Tvedestrand Bud Og Flytteservice AS | Transport & logistics | 2025 |
| Tvedestrand Butikkeiendom AS | Real estate | 2024 |
| Tvedestrand Bygg AS | Construction | 2023 |
| Tvedestrand Båtopplag AS | Wholesale & retail | 2019 |
| Tvedestrand Dans Trening & Trivsel Da | Education | 2003 |
| Tvedestrand Dekk AS | Wholesale & retail | 2026 |
| Tvedestrand Distribusjonsservice AS | Transport & logistics | 2015 |
| Tvedestrand Drosjesentral AS | Transport & logistics | 2004 |
| Tvedestrand Elektro AS | Construction | 2020 |
| Tvedestrand Elektromarked AS | Wholesale & retail | 2006 |
| Tvedestrand Fjordhotell Drift AS | Hospitality | 2022 |
| Tvedestrand Fysioterapi Og Rehabiliteringssenter AS | Health & social care | 2020 |
| Tvedestrand Interiør AS | Wholesale & retail | 1994 |
| Tvedestrand Kiropraktorklinikk AS | Health & social care | 2020 |
| Tvedestrand Lagerutleie AS | Transport & logistics | 1997 |
| Tvedestrand Legesenter Ans | Health & social care | 2000 |
| Tvedestrand Næringsområde AS | Real estate | 2012 |
| Tvedestrand Optikk AS | Wholesale & retail | 2006 |
| Tvedestrand Regnskapsbyrå AS | Professional & scientific | 1998 |
| Tvedestrand Storsenter AS | Real estate | 1989 |
| Tvedestrand Sykkelverksted AS | Other services | 2014 |
| Tvedestrand Tannlegene AS | Health & social care | 2025 |
| Tvedestrand Taxi Tjenester AS | Transport & logistics | 2021 |
| Tvedestrand Vekst AS | Real estate | 1977 |
| Tvedestranda Eiendom AS | Real estate | 2017 |
| Tvedestrandsposten AS | Information & communication | 1991 |
| TVK AS | Wholesale & retail | 2014 |
| Typhonen AS | Real estate | 2022 |
| Tømrermester Frydendal AS | Construction | 2014 |
| Unni Frisør AS | Other services | 2011 |
| Vantageone AS | Professional & scientific | 2022 |
| Varden Tvedestrand AS | Real estate | 2021 |
| Vatnegården AS | Real estate | 2023 |
| Vegarheim Pukkverk Og Entreprenør AS | Mining & quarrying | 1989 |
| Veggdesign Bygg AS | Construction | 2025 |
| Vegår Trestoff Og Energi AS | Manufacturing | 2025 |
| Velværehjørnet AS | Wholesale & retail | 2022 |
| Vennevannsveien 46 AS | Real estate | 2022 |
| Vennevannsveien 64 AS | Real estate | 2025 |
| Vennevannsveien SA | Real estate | 1988 |
| Verde Naturpuss AS | Construction | 2024 |
| Vere Trading AS | Wholesale & retail | 2022 |
| Vertshuset Tvedestrand AS | Hospitality | 2007 |
| Vestøl Holding AS | | 2012 |