| Strømsveien Eiendom AS | Real estate | 2002 |
| Stu Consulting AS | Professional & scientific | 2022 |
| Studio Mason AS | Professional & scientific | 2025 |
| Studio Nova AS | Other services | 2020 |
| STUDIO74 AS | Other services | 2022 |
| Stålbetong Konstruksjon AS | Construction | 2020 |
| Sulland Jessheim AS | Other services | 2002 |
| Summit Pro Holding AS | Other services | 2018 |
| Sumo Jessheim AS | Hospitality | 2017 |
| Sundbytunet Bar & Bryggeri AS | Hospitality | 2017 |
| Sundbytunet Eiendom AS | Real estate | 1997 |
| Sundvold Holding AS | | 2021 |
| Sunnas AS | Health & social care | 2023 |
| Supera AS | Information & communication | 2017 |
| Supero Omnia AS | | 2021 |
| Superwe AS | Real estate | 2016 |
| Surdeigmedv AS | Manufacturing | 2026 |
| Sustainable Growth AS | Wholesale & retail | 2018 |
| Svan AS | Health & social care | 2014 |
| Sven Myrvold AS | Wholesale & retail | 2025 |
| Svendsen Holdco AS | Wholesale & retail | 2022 |
| Svendsen Utemiljø AS | Administrative & support | 2015 |
| Svendsens Invest AS | | 2022 |
| SVL & Jee Holding AS | Other services | 2020 |
| Swebygg Ans | Construction | 1997 |
| Sylstad AS | Wholesale & retail | 2022 |
| Sylstad Holding AS | Wholesale & retail | 2022 |
| Syverstad Insurance Services AS | Professional & scientific | 2016 |
| Sælidmontasje AS | Construction | 2020 |
| Söderberg & Partners Romerike AS | | 2026 |
| Søgarden Bjørkemoen AS | Real estate | 2019 |
| Sønsteby Holding AS | | 2026 |
| Sørholtet Andelslag SA | Education | 2001 |
| Sørli + Walïn AS | Professional & scientific | 2017 |
| Sørlie Invest AS | | 2019 |
| Sørlie Visualisering Da | Professional & scientific | 2010 |
| T&E Entreprenør AS | Construction | 2024 |
| T&G Eiendom AS | Real estate | 2016 |
| T&G Holding AS | Financial services | 2017 |
| T.E.N Holding AS | Real estate | 2020 |
| T.H Valby Asfalt & Graving AS | Construction | 2017 |
| Taal Eiendom AS | Real estate | 2018 |
| Taal Holding AS | Real estate | 2017 |
| Taalesen Holding AS | Hospitality | 2005 |
| Taasen Holding AS | | 2022 |
| Tag Event AS | Arts & recreation | 2012 |
| Tag Safe IT AS | Information & communication | 2016 |
| Tak ÒG Innredning AS | Construction | 2025 |
| Takst & Malermester A.Magnus AS | Real estate | 2021 |
| Tande Transport AS | Transport & logistics | 2019 |
| Tanderø Holding AS | Real estate | 2021 |
| Tangenvegen Eiendom AS | Real estate | 2020 |
| Tannlegene Helgedagsrud Og Sæter AS | Health & social care | 2012 |
| Tannlegene Stensby Og Tran AS | Health & social care | 2015 |
| Tannrot AS | Health & social care | 2023 |
| Task Holding AS | Transport & logistics | 2005 |
| Taurito AS | Professional & scientific | 2018 |
| Tauroaasen AS | Real estate | 2016 |
| Taxi Romerike SA | Transport & logistics | 2017 |
| Taxi Viwe AS | Professional & scientific | 2026 |
| Team Regnskap Jessheim AS | Professional & scientific | 2009 |
| Team Service & Rep AS | Other services | 2022 |
| Techalliansen Norden AS | Professional & scientific | 2025 |
| Techwise AS | Information & communication | 2024 |
| Tek:Pro AS | Professional & scientific | 2019 |
| Teknisk Prosjekt Konsult AS | Professional & scientific | 2026 |
| Telerespons Da | Other services | 1991 |
| Tema Regnskap Jessheim AS | Professional & scientific | 1996 |
| Tempura House Avd. Jessheim AS | Hospitality | 2026 |
| Ten Takst & Eiendom AS | Real estate | 2020 |
| Teraks AS | Real estate | 2024 |
| Terje Nullmeyer AS | Transport & logistics | 2026 |
| Teta Vannrensing AS | Wholesale & retail | 2014 |
| Texa Design Norge AS | Wholesale & retail | 1998 |
| Texstyle Corporation AS | Wholesale & retail | 2019 |
| Teys Future AS | | 2022 |
| Teø Eiendom AS | Real estate | 2014 |
| Tfmc AS | Professional & scientific | 2018 |
| TG Graphic Design & Consult Nuf | Professional & scientific | 2015 |
| TG Grsaphic Design & Consult Invest | | 2015 |
| Tg-Renhold AS | Administrative & support | 2001 |
| Tg-Renhold Holding AS | Real estate | 2024 |
| Tg-Renhold Klinikk AS | Administrative & support | 2015 |
| Thai Take Away Da | Hospitality | 2010 |
| The Barber Club AS | Other services | 2024 |
| The Barber Club Jessheim Da | Other services | 2020 |
| The Cabin Crew AS | Professional & scientific | 2020 |
| The View Hafjell AS | Real estate | 2022 |
| Thorsen Regnskap AS | Professional & scientific | 2012 |
| Thørn Eiendom AS | Professional & scientific | 2015 |
| Thørn Gruppen AS | Professional & scientific | 2008 |
| Tiger Service AS | Administrative & support | 2010 |
| Tila AS | Real estate | 2022 |
| Tirilltoppen Holding AS | Transport & logistics | 2005 |
| Titoma Holding AS | Professional & scientific | 2018 |
| Tiurkroken Holding AS | Construction | 2024 |
| Tixe AS | Real estate | 2016 |
| TK Installasjon & Service AS | Construction | 2011 |
| Tl&Sn Engineering AS | Professional & scientific | 2020 |
| TM. Kjos AS | Construction | 2001 |