| Spetals Verk Holding AS | Real estate | 2025 |
| Spleismark AS | Real estate | 2012 |
| Spleismark Campus AS | Real estate | 2020 |
| Spleismark Handel AS | Real estate | 2017 |
| Spleismark Næring AS | Real estate | 2014 |
| Sportica Kongsvinger AS | Arts & recreation | 2015 |
| Squzo Invest AS | Real estate | 2011 |
| Stalro AS | Real estate | 2017 |
| Stantek AS | Manufacturing | 1978 |
| Stantek Eiendom AS | Manufacturing | 2004 |
| Stantek Holding AS | Manufacturing | 2005 |
| Stensmoen Eiendom AS | Construction | 2007 |
| Stereo Skis AS | Manufacturing | 2007 |
| Stjernekjøtt AS | Manufacturing | 1992 |
| Stolpe AS | Health & social care | 2005 |
| Storehaugen AS | Information & communication | 1995 |
| Storgata 55 Kongsvinger AS | Real estate | 2014 |
| Storgaten Park AS | Real estate | 2006 |
| Stream Media AS | Professional & scientific | 2018 |
| Strømstad Bygg Og Anlegg AS | Construction | 2012 |
| Studio G AS | Professional & scientific | 1990 |
| Støvkost.No AS | Wholesale & retail | 2021 |
| Sulland Kongsvinger AS | Other services | 1989 |
| Survaid AS | Professional & scientific | 1996 |
| Surveyor Landmåler AS | Professional & scientific | 2025 |
| Swe-Am Construction Da | Administrative & support | 2006 |
| Swedbygg AS | Construction | 2013 |
| Swemacimaging Nuf | Wholesale & retail | 2008 |
| Såg Och Betongborrning AB | Construction | 1997 |
| Såtvedt Bil AS | Wholesale & retail | 1999 |
| Søno AS | | 2025 |
| Sør-Hedmark Revisjon AS | Professional & scientific | 2002 |
| Sørliterminalen Stange AS | Real estate | 2009 |
| Søstrene Woll Da | Agriculture & fishing | 1983 |
| T Jonassen Holding AS | | 2026 |
| T. Ellingsen Holding AS | Real estate | 2022 |
| Taiga AS | Real estate | 2007 |
| Tajevegen 5 AS | Real estate | 2004 |
| Takservice I Kongsvinger AS | Construction | 2013 |
| Takskiferforum AS | Professional & scientific | 2010 |
| Tankpartner Holding AS | Other services | 2016 |
| Tannlege Jaghlasian AS | Health & social care | 2017 |
| Tannlege Klaus Ånerud AS | Health & social care | 2001 |
| Tannlege Kristiansen AS | Health & social care | 2024 |
| Tannlege Per Hafthun AS | Health & social care | 2016 |
| Tannlege Rotberget AS | Health & social care | 2023 |
| Tante Marie AS | Wholesale & retail | 1954 |
| Tar Utvikling 4 AS | | 2006 |
| Taugbøl Bil Og Maskin AS | Other services | 2019 |
| Taugbøl Consulting AS | Professional & scientific | 2019 |
| Taugbøl Invest AS | Real estate | 2007 |
| Taurus Holding AS | Real estate | 2022 |
| Taxi Express AS | Transport & logistics | 2024 |
| Taxi Kongsvinger SA | Transport & logistics | 2009 |
| Taxi Øst AS | Transport & logistics | 2021 |
| TB Trykkluftteknikk AS | Manufacturing | 2013 |
| Tco Holding AS | Financial services | 2012 |
| Team Huse Invest AS | | 2026 |
| Tedros Yacob AS | Wholesale & retail | 2023 |
| Tekstilservice AS | Wholesale & retail | 1999 |
| Telekiosken Kongsvinger AS | Wholesale & retail | 2005 |
| Terje Jacobsen AS | Transport & logistics | 2015 |
| Terraviva Valentina Fazijaj S.P. | Construction | 2011 |
| TG Rental & Sales AS | Administrative & support | 2012 |
| The Nail Lounge AS | Other services | 2024 |
| Thorr International AS | Financial services | 2008 |
| Tilsynservice AS | Administrative & support | 2026 |
| Tima's Hair & Beauty AS | Other services | 2018 |
| Tireline AS | Wholesale & retail | 2021 |
| TJ Reme AS | Professional & scientific | 2005 |
| TK Entreprenør AS | Construction | 2018 |
| TL Trading AS | Professional & scientific | 2013 |
| Tle Holding AS | Real estate | 2019 |
| TM Skog AS | Agriculture & fishing | 2012 |
| TN Prosjektplanlegging AS | Professional & scientific | 2016 |
| To Rør AS | Construction | 2024 |
| Tofialto AS | Real estate | 2013 |
| Toinro AS | Financial services | 2009 |
| Tommy Og Gunnars Transport AS | Transport & logistics | 1990 |
| Tonje Karlsen AS | Wholesale & retail | 2021 |
| Tony Henriksson | Agriculture & fishing | 2006 |
| Toolborg AS | Wholesale & retail | 2019 |
| Toolmarket AS | Manufacturing | 2007 |
| Topos Arkitektur Og Design AS | Professional & scientific | 2004 |
| Topp Reklame AS | Professional & scientific | 1990 |
| Torp Ellingsen Holding AS | Information & communication | 2021 |
| Torshaug Invest AS | Real estate | 2019 |
| Torvtransport 1 AS | Transport & logistics | 2022 |
| Total Auto Senter AS | Other services | 2015 |
| Totalsport AS | Administrative & support | 2014 |
| Toyota Sulland Kongsvinger AS | Other services | 1980 |
| Travel Center AS | Transport & logistics | 2021 |
| Trehusene På Flisa AS | Real estate | 2022 |
| Trehusene På Skarnes AS | Real estate | 2021 |
| Trell Design Ans | Professional & scientific | 2022 |
| TRH Holding AS | | 2026 |
| Trondheimsveien 456 AS | Real estate | 2021 |
| Trucktrading AS | Wholesale & retail | 2015 |
| TSM Leiligheter AS | Real estate | 2021 |
| Tycoon AS | Information & communication | 2018 |