| Sæthren Eiendom AS | Real estate | 1988 |
| Søndenfieldske Investeringscompagnie AS | | 2024 |
| Søndre Halfstad Holding AS | Financial services | 2024 |
| Sønsterud AS Sport Sykkelfabrikk | Wholesale & retail | 1939 |
| Sørensen Sport AS | Wholesale & retail | 2016 |
| Sørsdal Invest AS | | 2021 |
| Søråsveien Utvikling AS | Real estate | 2020 |
| T & R Service AS | Wholesale & retail | 2015 |
| T R Elektro Torry Ringkilen AS | Construction | 1997 |
| T. Nordvik Holding AS | | 2021 |
| Ta Klinikken AS | Health & social care | 2013 |
| Takt Kommunikasjon AS | Professional & scientific | 2026 |
| Taktgeber AS | | 2026 |
| Tall Rådgivning AS | Professional & scientific | 2005 |
| Tallaksrud Ved AS | Agriculture & fishing | 2025 |
| Talltrollet AS | Professional & scientific | 2014 |
| Tami Eiendom Og Finans AS | Real estate | 1978 |
| Tami Trading AS | Wholesale & retail | 2019 |
| Tamimi Import AS | Wholesale & retail | 2021 |
| Tandoori Palace Ski AS | Hospitality | 2025 |
| Tannkunsten AS | Health & social care | 2022 |
| Tannlege Cecilie Augestad AS | Health & social care | 2023 |
| Tannlege Chen Skjelbred AS | Health & social care | 2021 |
| Tannlege Hermansen Holding AS | Health & social care | 2005 |
| Tannlege Morten Ausland Eriksen AS | Health & social care | 2007 |
| Tatt Invest AS | Financial services | 2013 |
| Te Skjøld Investering AS | | 2024 |
| Tea Fusion Ski AS | Hospitality | 2022 |
| Teb Holding AS | Real estate | 2005 |
| Tede Holding AS | Professional & scientific | 2012 |
| Tefo AS | Professional & scientific | 2014 |
| TEG10 AS | Real estate | 2019 |
| Teknisk Design AS | Professional & scientific | 1991 |
| Teknolab AS | Wholesale & retail | 1980 |
| Telekiosken Ski AS | Wholesale & retail | 1999 |
| Terramoto AS | Financial services | 2017 |
| Tertia AS | Wholesale & retail | 2013 |
| Tette Avløp AS | Water & waste | 2017 |
| TG Invest AS | | 2025 |
| TG Rørservice AS | Construction | 2022 |
| Tgkarlsrud AS | | 2023 |
| The Room Ski AS | Education | 2025 |
| Thelma Louise Holding AS | | 2026 |
| Thema AS | Manufacturing | 2009 |
| Thomas International Norway AS | Education | 1990 |
| Thomas Leker Ski AS | Wholesale & retail | 2023 |
| Thomas Management Consulting AS | Professional & scientific | 2010 |
| Thomas Sacher | Professional & scientific | 2007 |
| Thorsteinsen Transport Og Graving AS | Transport & logistics | 2017 |
| Thricon AS | Information & communication | 2012 |
| Throwbacks AS | Information & communication | 2020 |
| Tiari Holding AS | Hospitality | 2025 |
| Tibr Holding AS | | 2025 |
| Tidenvår AS | Other services | 2017 |
| Tig Invest AS | Real estate | 2020 |
| Timpan Holding AS | Information & communication | 2021 |
| Tine Frisør AS | Other services | 2017 |
| Tingvold Holding AS | | 2024 |
| Tiram AS | Financial services | 2005 |
| Titt Inn Holding AS | Real estate | 2013 |
| Titt-Inn Leker AS | Wholesale & retail | 2022 |
| Tjæralin AS | Wholesale & retail | 2004 |
| TK Konsulent AS | Professional & scientific | 2020 |
| TK Revisjon AS | Professional & scientific | 2019 |
| Tma Utleie AS | Administrative & support | 2024 |
| TMF Service AS | Construction | 2020 |
| Tokehøj Agency AS | Wholesale & retail | 2018 |
| Tollefsen Transport AS | Transport & logistics | 2014 |
| Tomter Billakk AS | Wholesale & retail | 2011 |
| Tone Færøvik AS | Professional & scientific | 2014 |
| Topp Aerobic Da | Arts & recreation | 1999 |
| Torgveien Legekontor Da | Health & social care | 2018 |
| Tornerose Bio AS | Administrative & support | 2013 |
| Torolmen AS | | 2006 |
| Toso Invest AS | Transport & logistics | 2014 |
| Total Rørservice AS | Construction | 2007 |
| Trafikkpedagogen AS | Education | 2022 |
| Trafikkskolene Drift AS | Education | 2021 |
| Trallefabrikken AS | Wholesale & retail | 1998 |
| Tredimensional Elektronikk AS | Wholesale & retail | 1990 |
| Trevio AS | Real estate | 2026 |
| Tria Invest AS | Real estate | 2019 |
| Tribus AS | Real estate | 2016 |
| Trio Logistikk AS | Transport & logistics | 2023 |
| Trollcard AS | Manufacturing | 2010 |
| Trollsaas Invest AS | | 2018 |
| Truckservice AS | Manufacturing | 2010 |
| Trudvangata 18 AS | Real estate | 2018 |
| Trætteberg Rådgivning AS | Information & communication | 2020 |
| TS Invest Og Holding AS | | 2022 |
| Tsk-Invest AS | | 2026 |
| TST AS | Transport & logistics | 2005 |
| Tumay AS | Hospitality | 2013 |
| Tuntre Invest AS | | 2021 |
| Ture AS | Wholesale & retail | 2012 |
| Turkamera AS | Administrative & support | 2020 |
| TV1 Øst AS | Information & communication | 2016 |
| TV1.NO AS | Professional & scientific | 2025 |
| Temareiser AS | Administrative & support | 1988 |
| Tødden AS | Information & communication | 2023 |