| Trustcom AS | Information & communication | 2017 |
| Trygg-Invest AS | Real estate | 2005 |
| Tryland Data Center AS | Real estate | 2015 |
| Træleborgveien 11 Eiendom AS | Real estate | 2007 |
| Træleborgveien 15 AS | Real estate | 2013 |
| Træleborgveien 2 AS | Real estate | 2012 |
| Træleborgveien 7 AS | Real estate | 2022 |
| TS Eiendom 1 AS | Real estate | 2025 |
| TS Eiendom AS | Real estate | 2025 |
| TTL Holding AS | Professional & scientific | 2005 |
| Ttss Byggservice AS | Construction | 2024 |
| Ttss Eiendom AS | Real estate | 2021 |
| Ttss Holding AS | | 2024 |
| Tulip Regnskap AS | Professional & scientific | 2012 |
| Tun Arkitektur AS | Professional & scientific | 2013 |
| Tunsberg Eiendomsselskab AS | Real estate | 1993 |
| Tunsberg Medisinske Skole AS | Education | 2008 |
| Turid Molvik Holding AS | Financial services | 2020 |
| Turngaten 3 AS | Real estate | 2021 |
| Tvi Prosjekt AS | Professional & scientific | 2013 |
| Tw-H Holding AS | | 2025 |
| Tykkmark AS | Real estate | 2012 |
| Tyri Arkitekter AS | Professional & scientific | 2023 |
| Tyri Holding AS | Professional & scientific | 2023 |
| Tyrihans Holding AS | Administrative & support | 2023 |
| TZ Consulting AS | Information & communication | 2021 |
| Teig A/S | | 1988 |
| Tor H Bjørnstad AS | Real estate | 1994 |
| Tordenskjoldsgate 5 AS | Real estate | 1986 |
| Tønsberg & Færder Eiendomsmegling AS | Real estate | 2020 |
| Tønsberg Autoservice AS | Other services | 2010 |
| Tønsberg Bibelskole AS | Education | 2015 |
| Tønsberg Bil Og Bobil AS | Professional & scientific | 2026 |
| Tønsberg Bilpleie AS | Transport & logistics | 2021 |
| Tønsberg Brygge AS | | 2021 |
| Tønsberg Bygg Og Rehabilitering AS | Construction | 2003 |
| Tønsberg Båtutstyr AS | Wholesale & retail | 2020 |
| Tønsberg Drift AS | Wholesale & retail | 1961 |
| Tønsberg Eiendomsforvaltning AS | Real estate | 2020 |
| Tønsberg Elektriske AS | Construction | 1994 |
| Tønsberg Energistasjon AS | Wholesale & retail | 2021 |
| Tønsberg Farvehandel AS | Wholesale & retail | 1964 |
| Tønsberg Filmhus AS | Information & communication | 2025 |
| Tønsberg Fisk AS | Wholesale & retail | 2012 |
| Tønsberg Fotklinikk AS | Health & social care | 2017 |
| Tønsberg Fresh Food AS | Wholesale & retail | 2020 |
| Tønsberg Gruppen AS | Real estate | 2011 |
| Tønsberg Helse AS | Wholesale & retail | 2022 |
| Tønsberg Hud & Laserklinikk AS | Health & social care | 2016 |
| Tønsberg Invest AS | | 2024 |
| Tønsberg Kaffe AS | Hospitality | 2011 |
| Tønsberg Kiropraktorklinikk AS | Health & social care | 2010 |
| Tønsberg Kjøkkensenter AS | Wholesale & retail | 2021 |
| Tønsberg Lungeklinikk AS | Health & social care | 2019 |
| Tønsberg Manuell Terapi AS | Health & social care | 2023 |
| Tønsberg Medisinske Senter AS | Real estate | 2000 |
| Tønsberg Medlab AS | Wholesale & retail | 2002 |
| Tønsberg Møbler AS | Wholesale & retail | 2024 |
| Tønsberg Og Re Eiendomsmegling AS | Real estate | 2019 |
| Tønsberg Optiske AS | Wholesale & retail | 1997 |
| Tønsberg Osteopati Og Helse AS | Health & social care | 2024 |
| Tønsberg P-Hus AS | Real estate | 2014 |
| Tønsberg Samfunnshus SA | Real estate | 1950 |
| Tønsberg Sand- Og Tørrisblåsing AS | Administrative & support | 2017 |
| Tønsberg Sykkelservice Og Utleie AS | Other services | 2024 |
| Tønsberg Tak AS | Construction | 2019 |
| Tønsberg Tannclinique AS | Health & social care | 2021 |
| Tønsberg Tannhelse AS | Health & social care | 2012 |
| Tønsberg Tannregulering AS | Health & social care | 2015 |
| Tønsberg Ur AS | Wholesale & retail | 2023 |
| Tønsberg Ursenter | Wholesale & retail | 1985 |
| Tønsberg Vaskeri AS | Other services | 2021 |
| Tønsberg Yoga AS | Education | 2009 |
| Tønsberg Øre-Nese-Hals AS | Health & social care | 2013 |
| Tønsberg Øyelege Senter AS | Health & social care | 2026 |
| Tønsberg-Økonomisenter AS | Professional & scientific | 2025 |
| Tønsbergbier AS | Agriculture & fishing | 2026 |
| Tønsbergkirkenes Barnehager AS | Education | 2006 |
| Tønsberglivet AS | Professional & scientific | 2008 |
| Tønsbergs Blad AS | Information & communication | 1891 |
| Tønsbergs Turnforening Venner AS | Real estate | 2015 |
| Ua Helse Planet AS | Other services | 2025 |
| Uab Contus Norge Nuf | Administrative & support | 2013 |
| Uerstattelig AS | Professional & scientific | 2026 |
| Ufiltrert Klinikk AS | Other services | 2026 |
| Ugrass AS | Wholesale & retail | 2025 |
| Ulf Haraldsen AS | Professional & scientific | 2021 |
| Ullen Yarns AS | Wholesale & retail | 2025 |
| Ulma Holding AS | Real estate | 2018 |
| Ulterius AS | Professional & scientific | 2023 |
| Ulviken Motor Og Båtopplag AS | Transport & logistics | 2015 |
| Ulving Kunsthandel AS | Wholesale & retail | 1994 |
| Umpire Chartered AS | Professional & scientific | 1998 |
| Una Trading AS | Professional & scientific | 1987 |
| Ungcash AS | Administrative & support | 2021 |
| Unigro AS | Wholesale & retail | 2025 |
| Unite Performance AS | Arts & recreation | 2021 |
| Unity Pole & Aerial AS | Education | 2021 |
| Uno Mio SA | Professional & scientific | 2018 |
| Unomio Ans | Information & communication | 2021 |