| Tekniske AS | Professional & scientific | 2000 |
| Telecom Product AS | Wholesale & retail | 1998 |
| Tellus Vituz Art AS | Arts & recreation | 2025 |
| Tenden Advokatfirma Ans | Professional & scientific | 1990 |
| Terkus AS | Professional & scientific | 2011 |
| Terra Control AS | Professional & scientific | 1985 |
| Terranoesis AS | Professional & scientific | 2026 |
| TFD Invest AS | | 2023 |
| TGC Holding AS | Real estate | 2017 |
| TGC Invest AS | Real estate | 2010 |
| TGT5 AS | Real estate | 2019 |
| TH Flor AS | Wholesale & retail | 2013 |
| Thai Middag AS | Hospitality | 2016 |
| Thaulowsgate AS | Real estate | 2008 |
| The Box Tromsø AS | Real estate | 2019 |
| Thefri AS | Education | 2013 |
| Thep AS | | 2026 |
| Theresa Vu AS | | 2020 |
| Thermex Scandinavia AS | Wholesale & retail | 1968 |
| This Is Trine Hansen AS | Education | 2024 |
| THM Holding AS | Manufacturing | 2000 |
| Thofer Holding AS | | 2025 |
| Thomassen Advokatfellesskap Drift AS | Professional & scientific | 2004 |
| Thorvaldsen & Sønn Transport AS | Transport & logistics | 2012 |
| Thorwiik AS | Wholesale & retail | 2006 |
| Thueveien 10 AS | Real estate | 2019 |
| Tia AS | Wholesale & retail | 2012 |
| Tias AS | Hospitality | 2022 |
| Tilbudssjekkern AS | Construction | 2024 |
| Timotei Filimon AS | Construction | 2016 |
| Timx AS | Information & communication | 2016 |
| Tinget AS | Arts & recreation | 2022 |
| Tinimations AS | Information & communication | 2016 |
| Tipe AS | Wholesale & retail | 2024 |
| Titi AS | Financial services | 2016 |
| TK Finans AS | Financial services | 2006 |
| TK Retail AS | Wholesale & retail | 2015 |
| TNB Tønsberg AS | Wholesale & retail | 2001 |
| To Ask AS | Professional & scientific | 2020 |
| To Prosjekt AS | Real estate | 2018 |
| Toan AS | | 2019 |
| Tobecasa Invest AS | Real estate | 2019 |
| Toks Holding AS | Real estate | 2023 |
| Tolb Invest AS | | 2022 |
| Tollboden AS | Hospitality | 2021 |
| Tollbodgaten 14 C AS | Real estate | 2023 |
| Tollbodgaten 22 Tønsberg AS | Real estate | 2007 |
| Tolvkanten AS | Real estate | 2004 |
| Tolvsrød Bolig AS | Real estate | 2024 |
| Tolvsrød Eiendom AS | Real estate | 2017 |
| Tolvsrød Torg Holding AS | Real estate | 2024 |
| Tom G. Holding AS | | 2021 |
| Tomcon AS | Professional & scientific | 1989 |
| Tomteselskap BK5 AS | Real estate | 2023 |
| Tomteselskapet BK1 AS | Real estate | 2026 |
| Ton Kao AS | Hospitality | 2017 |
| Tone Nærø AS | Professional & scientific | 2007 |
| Tor Hansen Consult AS | Professional & scientific | 2015 |
| Tore Haraldstad & Co AS | Construction | 1999 |
| Tore W. Solum Holding AS | Real estate | 2005 |
| Torgersøya 11 AS | Real estate | 2010 |
| Torgevik AS | Real estate | 2005 |
| Torgy AS | Real estate | 2009 |
| Torgy Cryogenic LNG AS | Professional & scientific | 2010 |
| Torgy Mek. Industri AS | Manufacturing | 1999 |
| Torkel Bygg AS | Construction | 2016 |
| Tornerose Blomsteri AS | Wholesale & retail | 2013 |
| Torpstad Consulting AS | Professional & scientific | 2026 |
| Torstein Grytting Invest AS | Financial services | 2012 |
| Torvet 1 Teie AS | Real estate | 2017 |
| Torvet Frisør AS | Other services | 2001 |
| Torvet Invest Da | Professional & scientific | 1997 |
| Torvgangen 5-7 AS | Real estate | 2008 |
| Torvgaten 2 AS | Real estate | 2010 |
| Total HMS AS | Education | 2019 |
| Total Regnskap AS | Professional & scientific | 2020 |
| Total Spedisjon AS | Transport & logistics | 1988 |
| Totem Invest AS | Hospitality | 2024 |
| Totem Technology AS | Professional & scientific | 2002 |
| Tracksys Kurs Og Kompetanse AS | Information & communication | 2024 |
| Trade and Distribution Norway AS | Wholesale & retail | 2020 |
| Trade Part AS | Professional & scientific | 2014 |
| Trainor Elsikkerhet AS | Education | 2011 |
| Trainor Group AS | Education | 2020 |
| Transcon Engineering AS | Wholesale & retail | 2007 |
| Trehjørningen AS | | 2026 |
| Trend Norge Invest AS | Construction | 2020 |
| Trendco AS | Wholesale & retail | 2007 |
| Trepleiefirmaet Lilleby AS | Agriculture & fishing | 2011 |
| Tributo AS | | 2024 |
| Trimveien 3 AS | Wholesale & retail | 2013 |
| Trionor AS | Real estate | 2018 |
| Tritar Invest AS | | 2025 |
| Trivent AS | Information & communication | 2026 |
| Tro Holding AS | | 2021 |
| Trofast Da | Wholesale & retail | 2008 |
| Troll Regnskap AS | Professional & scientific | 2005 |
| Trost Holding AS | Financial services | 2016 |
| Trovator AS | Real estate | 2019 |
| Tructa Invest AS | Financial services | 2022 |