| TG Innkjøp AS | Professional & scientific | 2020 |
| TGL Oralkirurgi AS | Health & social care | 2023 |
| TH Aktiv AS | Manufacturing | 2009 |
| TH Jakt Og Friluft AS | Wholesale & retail | 2018 |
| TH Rør-Sveis AS | Manufacturing | 2008 |
| TH. Petersonsgate 2 AS | Real estate | 2005 |
| TH. Petersonsgate 4 AS | Real estate | 2017 |
| Thai Vi Sushi 3 AS | Hospitality | 2024 |
| Thams Holding AS | | 2025 |
| The Global Ensemble Theatre AS | Arts & recreation | 1997 |
| Thelmi Holding AS | | 2021 |
| Thib Eiendom AS | Real estate | 2023 |
| This Is a Fairy Tale AS | Arts & recreation | 2021 |
| Thohan AS | Real estate | 2005 |
| Thold AS | | 2019 |
| Thorder AS | Real estate | 2021 |
| Thoring AS | Real estate | 2011 |
| Thorne AS | Professional & scientific | 2023 |
| Thorvaldsen Eiendom AS | Real estate | 1991 |
| Three Chords Holding AS | Health & social care | 2013 |
| Thu Invest AS | Other services | 2019 |
| Thu Og Johansen AS | Wholesale & retail | 2006 |
| Thuja Planet AS | Wholesale & retail | 2016 |
| Thun Holding AS | | 2022 |
| Tico Holding AS | Professional & scientific | 2025 |
| Ticool AS | | 2025 |
| Tid & Kontroll AS | Information & communication | 2019 |
| Tiger Kebab Grill AS | Hospitality | 2012 |
| Tiger Nattklubb AS | Hospitality | 2021 |
| Tiki Bar AS | Hospitality | 2024 |
| Tiki Tilhenger AS | Administrative & support | 2005 |
| Tillbuddy AS | Information & communication | 2018 |
| Timbertech Norge AS | Wholesale & retail | 2012 |
| Time Out Renhold & Service AS | Administrative & support | 2024 |
| Tina,S Salong AS | Other services | 2013 |
| Tinkerblue AS | Professional & scientific | 2017 |
| Tinor AS | Wholesale & retail | 2023 |
| Tinymesh AS | Information & communication | 2011 |
| Tistedal Butikkeiendom AS | Real estate | 2015 |
| Tistel AS | | 2024 |
| Tivoli Amfi Teater Ba | Real estate | 1996 |
| Tiwa Holding AS | | 2022 |
| Tl-Gulliksen AS | Real estate | 2013 |
| Tl-Import AS | Wholesale & retail | 2023 |
| Tla Lagbygger AS | Professional & scientific | 2023 |
| TLJ Invest AS | | 2020 |
| Tmdue AS | Professional & scientific | 2021 |
| Tmgh AS | | 2025 |
| TMP Invest AS | Professional & scientific | 2021 |
| TN Bygg&Bad AS | Construction | 2024 |
| TNB Rygge AS | Wholesale & retail | 2023 |
| Toj AS | Real estate | 2010 |
| Tokali AS | Wholesale & retail | 2024 |
| Toko Holding AS | Real estate | 2014 |
| Tomasz Rudnicki AS | | 2025 |
| Tomoko AS | Financial services | 2005 |
| Tonheim Boligutvikling AS | Real estate | 2025 |
| Tonje Skinnarland AS | | 2025 |
| Topp Maskin AS | Administrative & support | 2023 |
| Toroma AS | Financial services | 2005 |
| Torp Butikk Eiendom AS | Real estate | 2018 |
| Total Consult AS | Real estate | 1931 |
| Tothe Invest Holding AS | Real estate | 2022 |
| Touchpoint Workwear AS | Wholesale & retail | 2024 |
| Towi Eiendom AS | Real estate | 2006 |
| TP Consulting AS | Professional & scientific | 2023 |
| TPV Holding AS | | 2022 |
| TR Renhold AS | Administrative & support | 2021 |
| Tradinno AS | Professional & scientific | 1999 |
| Tradinno Holding AS | Real estate | 2016 |
| Tradish Brewing Company AS | Manufacturing | 2025 |
| Tradish Holding AS | Manufacturing | 2025 |
| Tranquillity Base Ltd Nuf | | 2006 |
| Translyft AS | Real estate | 1994 |
| Transport Konsulenten AS | Transport & logistics | 2015 |
| Transportsentralen AS | Transport & logistics | 1987 |
| Travelnet Moss AS | Administrative & support | 2016 |
| Treasury + Finance AS | Professional & scientific | 2019 |
| TREES4CO2 AS | Professional & scientific | 2023 |
| TREES4SHOPPING AS | Administrative & support | 2016 |
| Trelar AS | Financial services | 2011 |
| Trenger Du AS | Information & communication | 2013 |
| Trigonor AS | Wholesale & retail | 1997 |
| Triks Ans | Information & communication | 2001 |
| TRIPPEL9 Gull Og Sølv Moss AS | Wholesale & retail | 2025 |
| Troldtekt AS | Construction | 2019 |
| Trolldalen Eiendom AS | Real estate | 2013 |
| Trollskogen Naturbarnehage SA | Education | 2002 |
| Trolltorget AS | Wholesale & retail | 2025 |
| Tronrud Engineering Moss AS | Manufacturing | 1987 |
| Tronvik Eiendom AS | Real estate | 2007 |
| Tronvik Gårdsbarnehage AS | Education | 2007 |
| Tronvikborg AS | Real estate | 1972 |
| Tronvikveien Mat AS | Wholesale & retail | 2014 |
| Tryggbygg 24 AS | Construction | 2024 |
| Trygt Innemiljø AS | Construction | 2019 |
| Trygve Halvorsen Holding AS | Wholesale & retail | 2004 |
| Trygve Plener AS | Professional & scientific | 1993 |
| Trygve Åsvestad AS | Financial services | 2005 |
| Trykk Nummer 1 AS | Manufacturing | 2024 |