| Skakstad Invest AS | Real estate | 2015 |
| Skapeladden & Co AS | Professional & scientific | 2014 |
| Skjelbredåsen Holding AS | Financial services | 2018 |
| Skogsentreprenørene Ans | Agriculture & fishing | 2001 |
| Skunkworks AS | Information & communication | 2025 |
| Skuterud Drift AS | Construction | 2021 |
| Skålien Holding AS | Construction | 2018 |
| Smart Liv AS | Arts & recreation | 2011 |
| Snarum Eiendom AS | Real estate | 2016 |
| Snarum Pukkverk AS | Mining & quarrying | 2014 |
| Sofies Holding AS | Real estate | 2016 |
| Solbakken Vannverk SA | Water & waste | 2020 |
| Solbakkin Ferieleiligheter AS | Real estate | 2021 |
| Solfang.No AS | Wholesale & retail | 2006 |
| Solid Bygg Og Betong AS | Construction | 2024 |
| Solknausen Invest AS | Real estate | 2012 |
| Sommerfryd Treningssenter Ans | Other services | 2007 |
| Spinnerifossen Kraftkompani AS | Energy | 2023 |
| Spirekontorene AS | Real estate | 2021 |
| Sponeåsen Eiendom AS | Real estate | 2016 |
| ST5 Holding AS | | 2020 |
| Statistical Consulting Services LLC | Administrative & support | 2012 |
| Stefferud Holding AS | Construction | 2019 |
| Steinbra Eiendomsutvikling AS | Real estate | 2020 |
| Stensby Entreprenør AS | Real estate | 2005 |
| Stenshus Eiendom AS | Real estate | 2017 |
| Stensrud Fossekompani AS | Energy | 2023 |
| Strandgården Brygge AS | Real estate | 2011 |
| Studio Norway Hår AS | Other services | 2019 |
| Sunn Hest AS | Wholesale & retail | 2021 |
| Supersmurf AS | | 2020 |
| SVH Drift AS | Arts & recreation | 2019 |
| Svingen Kafe Holding AS | Financial services | 2005 |
| Syme Holding AS | Information & communication | 2024 |
| Symetra AS | Wholesale & retail | 2002 |
| Sysle Eiendom AS | Real estate | 2011 |
| Sysle Utvikling AS | Real estate | 2024 |
| Sysletjernsveien SA | Real estate | 2018 |
| Sysprog AS | Professional & scientific | 2013 |
| Syversmyrveien SA | Real estate | 1979 |
| Søderlind Invest AS | Financial services | 2015 |
| Søndre Øren Holding AS | Real estate | 2021 |
| Søndre Øren Terrasse AS | Real estate | 2021 |
| T Grupper AS | Health & social care | 2023 |
| T. Catering AS | Hospitality | 2012 |
| T. Hovland AS | Transport & logistics | 2007 |
| T.E.Wolfram AS | Construction | 2023 |
| Taktekkermester B.Schramm AS | Construction | 2024 |
| Tanberg Tekstil AS | Wholesale & retail | 2011 |
| Tandberg MC AS | Wholesale & retail | 2013 |
| Tangerud AS | | 2012 |
| Tba Elektro AS | Wholesale & retail | 1992 |
| Tbs-Eiendom AS | Real estate | 2024 |
| Team Nilsen Anlegg Ltd Nuf | Construction | 2022 |
| Tekta Eiendom AS | Real estate | 2021 |
| Tekta Holding AS | Wholesale & retail | 2021 |
| Thale Design AS | Manufacturing | 1981 |
| Thorseth Eiendom AS | Real estate | 2014 |
| Tib Invest AS | Real estate | 2005 |
| Tidafar AS | Information & communication | 2015 |
| Til Avtalt Tid AS | Construction | 2015 |
| Tine Hartz AS | Arts & recreation | 2021 |
| TM Løkka Invest AS | | 2019 |
| TMH AS | Real estate | 2017 |
| Tolk Og Røvere AS | | 2025 |
| Tom Røste AS | Manufacturing | 2005 |
| Tom W Invest AS | Financial services | 2014 |
| Tor Ivar Martinsen Transport AS | Transport & logistics | 1989 |
| TSD Invest AS | | 2021 |
| TTR Holding AS | Construction | 2020 |
| Tveføtrud Eiendom AS | Real estate | 2014 |
| TW Eiendom AS | Real estate | 2014 |
| Tynningsdrift AS | Agriculture & fishing | 2006 |
| Tyr Holding AS | Wholesale & retail | 2005 |
| Tyri Eiendom Ans | Real estate | 1990 |
| Tyrifjord Fisk AS | Agriculture & fishing | 2012 |
| Tyrifjord Holding AS | Hospitality | 2005 |
| Tyrifjord Hotell AS | Hospitality | 1988 |
| Tyrifjord Hotell Eiendom AS | Hospitality | 2015 |
| Tørre & Skretteberg Ans | Construction | 1994 |
| Tørre & Skretteberg AS | Construction | 2016 |
| Ulera AS | Wholesale & retail | 2007 |
| Unimets AS | Construction | 2018 |
| Ute Og Aktiv Utleie AS | Administrative & support | 2015 |
| Va-Data AS | Professional & scientific | 2024 |
| Valstad & Sønsterud Ans | Real estate | 1997 |
| Vanco AS | Administrative & support | 2023 |
| Vann På Mølla AS | Real estate | 2019 |
| Varp Eiendom AS | Real estate | 2006 |
| Varp Entreprenør AS | Construction | 2013 |
| Varp Rør AS | Construction | 2018 |
| Vesetrud AS | Professional & scientific | 2014 |
| Veteranbåten Greven Ba | Other services | 2005 |
| Viken Bygg & Takst AS | Construction | 2019 |
| Viker Helse AS | Health & social care | 2022 |
| Vikersund Auto AS | Other services | 2021 |
| Vikersund Bad Eiendom AS | Health & social care | 1918 |
| Vikersund Bad Rehabiliteringssenter AS | Health & social care | 1992 |
| Vikersund Bilsenter AS | Wholesale & retail | 2008 |
| Vikersund Blåseisolering AS | Construction | 2021 |