| Tangen Allé 1 AS | Real estate | 2022 |
| Tannhjørnet Krøgenes AS | Health & social care | 2024 |
| Tannlege Babak Momtaz AS | Health & social care | 2023 |
| Tannlege Cecilie Terjesen AS | Health & social care | 2025 |
| Tannlege Jon Egil T. Fiane AS | Health & social care | 2014 |
| Tannlege Lars-Olof Bergman AS | Health & social care | 1988 |
| Tannlege Synnøve Anette Terjesen AS | Health & social care | 2013 |
| Tannlege Vegard Berg AS | Health & social care | 2025 |
| Tannlegene Bente Og Vegard Berg AS | Health & social care | 2011 |
| Tannlegene Lyngtveit Lindland AS | Health & social care | 2019 |
| Tannlegespesialistene Bergman AS | Health & social care | 2014 |
| Taxi Agder 41 AS | Transport & logistics | 2018 |
| Taxi Invest AS | Wholesale & retail | 2015 |
| TBGT5 AS | Real estate | 2017 |
| TC Capital AS | | 2023 |
| Te Terjesen Consulting AS | Information & communication | 2022 |
| Team Trafikkskole Arendal AS | Education | 2021 |
| Teaterplassen 1 Ans | Real estate | 2004 |
| Teaterplassen AS | Real estate | 2003 |
| Tekna Holding ASA | Energy | 2020 |
| Teknisk Hylle AS | Construction | 2020 |
| Teknofob AS | | 2025 |
| Teknologiveien 5A AS | Real estate | 2022 |
| Teknologiveien 5B AS | Real estate | 2022 |
| Teknologiveien 7 AS | Real estate | 2022 |
| Telenor Maritime AS | Information & communication | 2002 |
| Tellefsen Holding AS | Real estate | 2005 |
| Tempus Invest AS | Professional & scientific | 2007 |
| Terjesen Elektronikk AS | Wholesale & retail | 2011 |
| Terkelsen Trafikkskole AS | Education | 1985 |
| Ternen - AS | Hospitality | 2006 |
| Teth AS | Administrative & support | 1998 |
| TG Bil & Båt AS | Wholesale & retail | 2019 |
| Thaloran AS | Professional & scientific | 2021 |
| Tharend Group AS | Hospitality | 2019 |
| The 4 Investment AS | Administrative & support | 2021 |
| Thomic AS | Manufacturing | 2005 |
| Thomic Eiendom AS | Real estate | 2018 |
| Thor Egeberg AS | Health & social care | 1993 |
| Thorsdahl Invest AS | Real estate | 2015 |
| Thømt Sikkerhet AS | Construction | 2018 |
| Tibby Holding AS | | 2024 |
| Timevyn AS | Information & communication | 2025 |
| Tira Invest AS | Manufacturing | 2018 |
| Titt AS | Real estate | 2023 |
| TJ Aasen Consulting AS | Professional & scientific | 2024 |
| TK Bolig AS | Construction | 2015 |
| TNB Arendal AS | Wholesale & retail | 2006 |
| TNL AS | Real estate | 2019 |
| To Brings AS | | 2023 |
| Togos AS | Real estate | 2019 |
| Tolgen Holding AS | | 2022 |
| Tollbodgaten 2 AS | Real estate | 1995 |
| Tollbodgaten 3 Arendal AS | Real estate | 2006 |
| Tor Karlsen AS | Education | 2026 |
| Torbjørnsbu 21 AS | Real estate | 2001 |
| Torbjørnsbu Eiendom AS | Other services | 2020 |
| Torfo AS | Professional & scientific | 1999 |
| Tornli AS | Construction | 2016 |
| Torungen Utvikling AS | | 2023 |
| Torvet 10 Eiendom AS | Real estate | 2009 |
| Torvet 11 AS | Manufacturing | 2013 |
| Torvet Herrefrisør AS | Other services | 2022 |
| Torvgata 2 AS | Real estate | 2018 |
| Torvgata 7 AS | Real estate | 1998 |
| Torvgaten 5 AS | Real estate | 2019 |
| Torvgaten 8-10 AS | Real estate | 2022 |
| Total Service AS | Construction | 1996 |
| Total Team Eiendom AS | Real estate | 2004 |
| Totland Gruppen AS | | 2025 |
| Toves Trading AS | Wholesale & retail | 2020 |
| TR Invest AS | Real estate | 2014 |
| Tr-L Holding AS | | 2025 |
| Trafo Arkitektur AS | Professional & scientific | 2010 |
| Traftec AS | Construction | 2011 |
| Transport-Service AS | Transport & logistics | 2014 |
| Transport-Service Eiendom AS | Real estate | 2025 |
| Traveling Beauty Nurse AS | Health & social care | 2024 |
| Trend Mote AS | Wholesale & retail | 2003 |
| Trendy Bygg Og Transport AS | Transport & logistics | 1996 |
| Treno AS | Arts & recreation | 2010 |
| Trio Bilskadesenter AS | Other services | 2022 |
| Tripp AS | Real estate | 1994 |
| TRN Drift II AS | Construction | 2023 |
| TRN Holding AS | Construction | 2021 |
| Tromøy Eiendom AS | Real estate | 2023 |
| Tromøy In-Vest AS | Financial services | 2024 |
| Tromøy Regnskaps-Service AS | Professional & scientific | 2018 |
| Tromøysund Brygge AS | Real estate | 2005 |
| Trond Tveiten Trafikkskole AS | Education | 2022 |
| Trygg Sjø AS | Education | 2025 |
| Trygve Jensen Bygg AS | Real estate | 2011 |
| Trygve Rønning Eiendom AS | Real estate | 2024 |
| Trygve Rønning Invest AS | Real estate | 2018 |
| TT Trening AS | Arts & recreation | 2023 |
| TV Agder AS | Information & communication | 2013 |
| Tveitevoll Fitness AS | Education | 2026 |
| Twbank Project AS | Information & communication | 2017 |
| TWR Bygg AS | Construction | 2018 |
| TWR Eiendom AS | Real estate | 2018 |