| TO3NET AS | Wholesale & retail | 2005 |
| Toa Holding AS | | 2025 |
| Tob Invest AS | | 2005 |
| Tobienborg Låve AS | Real estate | 2020 |
| Tobija Invest AS | | 2025 |
| Tobimo AS | Real estate | 1997 |
| Toc AS | Construction | 2011 |
| Tofire AS | Construction | 2004 |
| Tofiresyv AS | Real estate | 2016 |
| Tofiretolv AS | Real estate | 2017 |
| Tofo AS | Real estate | 2009 |
| Tofte Eiendom AS | Real estate | 2025 |
| Tofteland AS | Real estate | 2021 |
| Togo Holding AS | Information & communication | 2016 |
| Tohon AS | Real estate | 2005 |
| Toji AS | | 2021 |
| Tokrini AS | Administrative & support | 2021 |
| Tol 24 AS | Hospitality | 2008 |
| Tolfsen Investering AS | Real estate | 2007 |
| Toli Invest AS | Real estate | 2006 |
| Tolk 24 AS | Professional & scientific | 2022 |
| Tollbodgata 7 AS | | 2026 |
| Tollbodgaten 3 AS | Real estate | 2014 |
| Tollbodgaten 36 AS | Real estate | 2017 |
| Tollbodgaten 63 AS | Real estate | 2004 |
| Tollbodgaten 9 AS | Real estate | 2005 |
| Tollefsrud Holding AS | Professional & scientific | 2006 |
| Tollerød AS | Real estate | 2014 |
| Tollevik Invest AS | | 2022 |
| Tollfest AS | Real estate | 2022 |
| Tolv Trær AS | Real estate | 2020 |
| Tom Barken Agenturer AS | Administrative & support | 2025 |
| Tomana Eiendom AS | Real estate | 2022 |
| Tomatgutta AS | Agriculture & fishing | 2021 |
| Tombola AS | | 2020 |
| Tomoharu AS | Administrative & support | 2015 |
| Tomt 1 (M54) AS | Real estate | 2013 |
| Tomt 11 AS | Real estate | 2014 |
| Tomt Skibåsen 28 AS | Real estate | 2025 |
| Tonar Invest AS | | 2020 |
| Tone Invest AS | | 2022 |
| Tonic Holding AS | | 2025 |
| Tonstad Fysioterapi Og Trening AS | Health & social care | 2021 |
| Tony J Higginson AS | Arts & recreation | 2026 |
| Toolsinvent AS | Wholesale & retail | 2011 |
| Top Realestate AS | Real estate | 2025 |
| Top-Eiendom AS | Real estate | 2021 |
| Top-Holding AS | Professional & scientific | 2023 |
| TOP1 Holding AS | Wholesale & retail | 2020 |
| Topdalsfjorden Utvikling AS | Real estate | 2005 |
| Topedersen Holding AS | | 2023 |
| Tophdal AS | Real estate | 2007 |
| Topo Gruppen AS | Real estate | 2009 |
| Topo Utvikling AS | Real estate | 1998 |
| Topout AS | | 2026 |
| Topp Tek Bygg AS | Real estate | 1989 |
| Topp Tek Bygg KS | Real estate | 1989 |
| Topstad Eiendom AS | Health & social care | 2015 |
| Tor Moseidjord Holding AS | Professional & scientific | 2018 |
| Tor Og Odin Collection AS | Other services | 2021 |
| Tordenskjolds Eiendom AS | Real estate | 2022 |
| Tordenstierne Antikk Da | Wholesale & retail | 2001 |
| Tordfest AS | Real estate | 2009 |
| Torghatten Eiendom AS | Real estate | 2001 |
| Torgplassen AS | Real estate | 2007 |
| Torgrim Hansen AS | Manufacturing | 2011 |
| Torgrimsen Eiendom AS | Construction | 2024 |
| Torgrimsen Holding AS | Real estate | 2011 |
| Tori Wrånes AS | Arts & recreation | 2019 |
| Torinokledet.No AS | Information & communication | 2013 |
| Torjesen Jernvare AS | Wholesale & retail | 1972 |
| Torjus AS | Professional & scientific | 2003 |
| Torjussen Consulting AS | Administrative & support | 2012 |
| Torjussen Invest AS | | 2026 |
| Tormar Eiendom AS | Real estate | 2024 |
| Tormod Bragdø AS | Construction | 2000 |
| Torrep Invest AS | Information & communication | 2005 |
| Torrey Invest AS | | 2021 |
| Torridal Legekontor AS | Health & social care | 2019 |
| Torridalsveien 14 AS | Real estate | 2011 |
| Torridalsveien Kolonial AS | Hospitality | 1998 |
| Torsbudalen Senter AS | Real estate | 2015 |
| Torsgaten Holding AS | Real estate | 2011 |
| Torskjær AS | Professional & scientific | 2019 |
| Torvbygget AS | Real estate | 1976 |
| Torve Strandeplass Bryggesameie AS | Arts & recreation | 2025 |
| Torvet Eiendomsinvest AS | Real estate | 2021 |
| Torvet KRS AS | Transport & logistics | 2021 |
| Torvik Consulting AS | Professional & scientific | 2014 |
| Torvkvartalet AS | Real estate | 2004 |
| Torvmoen 2 AS | Real estate | 2024 |
| Torvparkering AS | Transport & logistics | 2002 |
| Tosammen Interiør AS | Wholesale & retail | 2016 |
| Tospannet AS | | 2025 |
| Toyota Sør AS | Other services | 1987 |
| TP Vietmat AS | Hospitality | 2019 |
| TPL Byggmesterfirma AS | Construction | 2001 |
| Trainee Sør AS | Administrative & support | 2007 |
| Traktor- Og Maskindeler Sør AS | Wholesale & retail | 1991 |
| Trandheim Utvikling AS | Real estate | 2018 |