| STORGATA-22 AS | Real estate | 2018 |
| Storgaten 35 AS | Real estate | 1998 |
| Storgaten 42 AS | Real estate | 1967 |
| Stormek AS | Manufacturing | 2013 |
| Stormyhq Invest AS | Real estate | 2018 |
| Straidog AS | Information & communication | 2015 |
| Strandpromenaden Cafe Ans | Hospitality | 1994 |
| Stromness Eiendom AS | Real estate | 1992 |
| Studio Mudder AS | Manufacturing | 2023 |
| Subhold AS | Construction | 2023 |
| Subtech Engineering AS | Professional & scientific | 2019 |
| Suderra AS | Information & communication | 2026 |
| Svein Jacobsen Holding AS | Construction | 2023 |
| SWJ Holding AS | Professional & scientific | 2014 |
| SWJ Management AS | Professional & scientific | 2025 |
| Sykkelsalongen Horten AS | Wholesale & retail | 1973 |
| Symmetri AS | Professional & scientific | 2012 |
| Symmetri Rådgivning AS | Professional & scientific | 2024 |
| Syperle & Kurs AS | Wholesale & retail | 2021 |
| Systech AS | Manufacturing | 2009 |
| Så Lenge Skuta Kan Gå Da | Education | 2000 |
| Såheim Eiendom AS | Real estate | 2025 |
| Såheim Handel AS | Real estate | 2025 |
| Såheim Holding AS | Real estate | 2025 |
| Søkt AS | Professional & scientific | 2023 |
| Sør-Øst Transport AS | Transport & logistics | 2017 |
| Sørdal Holding AS | | 2024 |
| Sørsdal Holding AS | Construction | 2016 |
| T & T - Eiendom AS | Construction | 2012 |
| T & T Andersen AS | Real estate | 2021 |
| T & T Bygg AS | Construction | 2006 |
| T & T Eiendomsinvest AS | Real estate | 2021 |
| T O T Y Handelsbolag | Manufacturing | 2003 |
| T Og N Eiendom AS | Real estate | 2011 |
| T Og T Drift AS | Wholesale & retail | 2020 |
| T5 Eiendom AS | Real estate | 2015 |
| Tagsko Holding AS | | 2024 |
| Takst Østlandet AS | Professional & scientific | 2010 |
| Talentai AS | Information & communication | 2025 |
| Tangen Ingeniør- Og Arkitektkontor AS | Professional & scientific | 2012 |
| Tannhelsehuset AS | Health & social care | 2001 |
| Tannlege Gezelle Meerburg AS | Health & social care | 2021 |
| Tannlege Nina Landquist AS | Health & social care | 2016 |
| Tannlege Petter Haugen AS | Health & social care | 2021 |
| TAXI3 AS | Transport & logistics | 2006 |
| Tcap AS | Construction | 2015 |
| TD Skilt Og Profilering AS | Professional & scientific | 2017 |
| Team Trophy Ans | | 1991 |
| Team-G AS | Information & communication | 2022 |
| Teba Holding AS | Real estate | 2005 |
| Technord Ans | Manufacturing | 1993 |
| Technord AS | Professional & scientific | 2012 |
| Tek-Utvikling AS | Transport & logistics | 2019 |
| Teppemagasinet AS | Wholesale & retail | 1992 |
| Tessbo AS | Financial services | 2005 |
| Tettenborn Holding AS | Information & communication | 2020 |
| Texi Electronics AS | Manufacturing | 1986 |
| TG Brannteknikk AS | Professional & scientific | 2022 |
| TG Construction AS | Construction | 2022 |
| TG Eiendom 1 AS | Real estate | 2024 |
| TG Eiendom Øst AS | Real estate | 2022 |
| Tg-Holding AS | Real estate | 2005 |
| TGT9-15 AS | Real estate | 2024 |
| TH Økonomi AS | Professional & scientific | 2009 |
| The Golden Hands AS | Other services | 2020 |
| The Promised Land AS | | 2019 |
| Theie Invest AS | | 2026 |
| Thorkel Olsen Invest AS | Financial services | 2017 |
| Thuegaten 2 Eiendom AS | Real estate | 2008 |
| Tilma AS | Professional & scientific | 2008 |
| Tim Thomas AS | Agriculture & fishing | 2017 |
| Tind Elektroteknikk AS | Construction | 2023 |
| Tinden Hotell AS | Hospitality | 2007 |
| Tings AS | Professional & scientific | 2022 |
| TNB Horten AS | Wholesale & retail | 2018 |
| To Gode Venner Holding AS | Construction | 2022 |
| Tobada AS | Professional & scientific | 2022 |
| Todax AS | Financial services | 2005 |
| Tomo Industrier AS | Manufacturing | 2016 |
| Tomtegata 6 AS | Construction | 2016 |
| Tonsåsen AS | Real estate | 2023 |
| Toogførti AS | | 2024 |
| Topp Tak AS | Construction | 2021 |
| Torggt 12 AS | Real estate | 2005 |
| Torggården Trend AS | Wholesale & retail | 2012 |
| Torghatten Sør AS | Transport & logistics | 1995 |
| Torida Holding AS | Financial services | 2017 |
| Torka AS | Information & communication | 2016 |
| Torsheller Invest AS | | 2021 |
| Torstensrud Eiendom AS | Real estate | 2023 |
| Torvet 6 a AS | Real estate | 2004 |
| Torås Invest AS | | 2006 |
| Tov Holding AS | | 2020 |
| Tovica AS | Real estate | 2021 |
| Traktern AS | Hospitality | 2023 |
| Transport & Sjåførservice Invest | Real estate | 2016 |
| Travl AS | Information & communication | 2022 |
| Trebjønn AS | Professional & scientific | 2023 |
| Trex Holding AS | | 2020 |
| Trimveien Barnehage Da | Education | 2000 |