| Soland AS | Professional & scientific | 2021 |
| Solberg Eiendom AS | Real estate | 1982 |
| Solbrå Invest AS | Real estate | 2011 |
| Solunix AS | Information & communication | 2025 |
| Sortimo AS | Wholesale & retail | 2017 |
| Soto Handel AS | Wholesale & retail | 2010 |
| Spare Parts Service AS | Wholesale & retail | 2003 |
| Speedometer Service AS | Other services | 2025 |
| Spirax Sarco AS | Wholesale & retail | 1986 |
| Sport 1 Skedsmo AS | Wholesale & retail | 2018 |
| Sqlynx AS | Information & communication | 2004 |
| SR Consulting AS | Professional & scientific | 2025 |
| SS Auto AS | Wholesale & retail | 2025 |
| Stabilisator AS | Financial services | 2014 |
| Stai Hotell AS | Hospitality | 2018 |
| Stall Wærhaug AS | Agriculture & fishing | 2025 |
| Statera Holding AS | Professional & scientific | 2017 |
| Stato Bygg AS | Construction | 2021 |
| Staut Eiendom AS | Real estate | 2025 |
| Steier Invest AS | Real estate | 2007 |
| Stikk Innom Hos Berit - Akupunktur Og Medisinsk Yoga AS | Health & social care | 2013 |
| Stillas Spesialisten AS | Construction | 2016 |
| Stjerne Holding AS | Administrative & support | 2005 |
| Storbohus AS | Construction | 2019 |
| Strande Invest AS | Financial services | 2013 |
| Stranum International Properties AS | Real estate | 2013 |
| Strong Holding AS | Real estate | 2019 |
| Strømmen Bilservice AS | Other services | 1999 |
| Strømmen Dreieverksted AS | Manufacturing | 2010 |
| Strømmen Keramiske Håndverk AS | Construction | 1997 |
| Stuf AS | Information & communication | 2005 |
| Styrke Invest AS | | 2025 |
| Sub Optimal AS | Manufacturing | 2025 |
| Sushi Kokken Skedsmo AS | Hospitality | 2019 |
| Svetsprodukter Jacquet AB | Wholesale & retail | 2003 |
| Swedlock Norge AS | Wholesale & retail | 2020 |
| Sæther Elektriske Holding AS | Construction | 2015 |
| Sæves Gravsteiner AS | Manufacturing | 2009 |
| T-Hf Holding AS | | 2021 |
| T.E.K AS | | 2021 |
| T.O. Gabrielsen Holding AS | | 2023 |
| Taekwondo Sports Da | Wholesale & retail | 2011 |
| Takst Invest AS | Real estate | 2019 |
| Tamtron AS | Wholesale & retail | 1971 |
| Tangerud Invest AS | | 2022 |
| Tannlege Rolf Øines AS | Health & social care | 2025 |
| Tassen Bar Og Bistro AS | Professional & scientific | 2021 |
| TCN Invest AS | | 2026 |
| Teamplayer AS | Education | 2023 |
| Teaterkonsept AS | Arts & recreation | 2018 |
| Telekompetanse AS | Information & communication | 2002 |
| Telestore Skedsmo Senter AS | Manufacturing | 2024 |
| Telmo Control AS | Wholesale & retail | 1971 |
| Terminal Og Truck AS | Transport & logistics | 2020 |
| Thejo AS | | 2023 |
| Thelma-Holding AS | | 2019 |
| Three Star Group AS | Information & communication | 1998 |
| Thrymr AS | Professional & scientific | 2025 |
| Tiensu AI Holding AS | Other services | 2017 |
| Tinka Norge Nuf | Real estate | 2009 |
| TKB Byggservice AS | Construction | 2022 |
| TL Eiendom AS | Real estate | 1987 |
| To Pinner Da | Information & communication | 2016 |
| Toge Invest AS | Real estate | 2013 |
| Tollnes AS | Real estate | 2020 |
| Tom B. Johansen Invest AS | | 2020 |
| Tosim AS | Professional & scientific | 2014 |
| Total Eiendomsservice AS | Administrative & support | 2013 |
| Total Partner AS | Administrative & support | 2006 |
| Total Uteservice AS | Construction | 2019 |
| Totoma AS | Education | 2022 |
| Trafikkforum Servicesenter AS | Wholesale & retail | 1992 |
| Transnett AS | Professional & scientific | 2017 |
| Transportsentralen Lillestrøm SA | Transport & logistics | 1985 |
| Transportservice Lillestrøm AS | Transport & logistics | 2006 |
| Transportutstyr AS | Wholesale & retail | 1986 |
| Tre Kroner Eiendom AS | | 2017 |
| Treenode AS | Information & communication | 2026 |
| Treningsfrue AS | Professional & scientific | 2017 |
| Trimax Teknisk Elektronikk AS | Wholesale & retail | 1994 |
| Troll Bilverksted AS | Other services | 2020 |
| Troll Boks AS | Transport & logistics | 2017 |
| Troll Deler AS | Other services | 2024 |
| Trollparts AS | Construction | 2022 |
| Trollparts Ålesund AS | Wholesale & retail | 2024 |
| Trollrental Holding AS | Construction | 2022 |
| Trondheimsveien 183 AS | Real estate | 2016 |
| Truckpartner Norge AS | Wholesale & retail | 2012 |
| Trulavi Invest AS | Administrative & support | 2005 |
| Tsss Holding AS | | 2025 |
| TST Renovering AS | Real estate | 2015 |
| Ttconsult AS | Professional & scientific | 2022 |
| Tunhus II SA | Other services | 1973 |
| Tunhusene 1 SA | Real estate | 2016 |
| Tyr Group AS | Professional & scientific | 2009 |
| Tyriveien 9 AS | Real estate | 2015 |
| Ultra Renhold AS | Administrative & support | 2025 |
| Unipos AS | Wholesale & retail | 2012 |
| Upright AS | | 2020 |
| Urskog Invest AS | | 2021 |