| Seccon AS | Professional & scientific | 2008 |
| Secmetrics AS | Information & communication | 2016 |
| Secore Services AS | Information & communication | 2023 |
| Seenor AS | Wholesale & retail | 2012 |
| Selvklart AS | Information & communication | 2020 |
| Sen Eiendom AS | Real estate | 2021 |
| Senho Holding AS | | 2005 |
| Sentrum Bil & Karosseri AS | Other services | 1987 |
| Sentrum Byliv AS | Arts & recreation | 2022 |
| Sentrum Gardiner AS | Wholesale & retail | 2011 |
| Sentrum Vaktmestertjenester Da | Administrative & support | 2024 |
| Sentrumlegene Gjøvik AS | Health & social care | 2009 |
| Sentrumsgata 9-13 AS | Real estate | 2022 |
| Sentrumstomter Holding AS | Real estate | 2008 |
| Servatur Holding AS | Real estate | 2007 |
| Service Og Eiendom AS | Real estate | 2002 |
| Servicemesteren AS | Administrative & support | 2020 |
| Servicemesteren Rise AS | Administrative & support | 2017 |
| Serwent Brdr Grønnerud AS | Water & waste | 2013 |
| Sesam Oppland AS | Wholesale & retail | 2016 |
| Sge AS | Real estate | 2016 |
| SGR Holding AS | Real estate | 2019 |
| Shalom AS | Wholesale & retail | 2016 |
| Shaping Colour AS | Professional & scientific | 2012 |
| Shaqura AS | Real estate | 2015 |
| Showstart AS | Arts & recreation | 2016 |
| Siak AS | Real estate | 2005 |
| Siau Holding AS | | 2022 |
| Sicher Sense AS | Professional & scientific | 2021 |
| Siegel AS | | 2016 |
| Sifu Invest AS | | 2022 |
| Siggeruds Gate 4 AS | Real estate | 2021 |
| Sigkarl AS | Agriculture & fishing | 2024 |
| Sigr Eiendom AS | Real estate | 2020 |
| Sigrun G H Holding AS | Financial services | 2005 |
| Sigurd Østliensveg 3 AS | Real estate | 2021 |
| Sikkerhet Innlandet AS | Administrative & support | 2008 |
| Sikten Eiendom AS | Real estate | 2011 |
| Silje Myren AS | Financial services | 2020 |
| Siljoh AS | Administrative & support | 2014 |
| Silvercon Bemanning AS | Administrative & support | 2021 |
| Simaols Holding AS | Wholesale & retail | 2022 |
| Simen FT Holding AS | | 2020 |
| Simto AS | Real estate | 2002 |
| Simufort AS | Information & communication | 2021 |
| Sinced Eiendom AS | Real estate | 2025 |
| Sisa AS | Hospitality | 2005 |
| Sisa Eiendom AS | Real estate | 2015 |
| Sit Soppen Studentbarnehage AS | Education | 2022 |
| Siv Ing Olaf Syljuåsen Entreprenørforretning AS | Real estate | 1968 |
| Siv's Hårstudio AS | Other services | 2014 |
| Sivsanger Da | Wholesale & retail | 2025 |
| Sjusjøen Utvikling AS | Real estate | 2001 |
| SK Malerservice AS | Construction | 2024 |
| Skarkerud Gård Ans | Agriculture & fishing | 2005 |
| Skarkerudvegen SA | Real estate | 1959 |
| Skaso AS | Real estate | 2015 |
| Skattum Holding AS | Real estate | 2005 |
| Skattum Invest AS | Real estate | 2000 |
| Skattum Vekst AS | Real estate | 2018 |
| Skaugerud Holding AS | Real estate | 2016 |
| Skaugom Hundesenter AS | Other services | 2026 |
| Skaugom Invest AS | Financial services | 2018 |
| Skaun Eiendom AS | Real estate | 2000 |
| Skifr Eiendom AS | Real estate | 2025 |
| Skinmed.No AS | Health & social care | 2019 |
| Skinstad AS | Real estate | 2008 |
| Skjerven Biopark AS | Real estate | 2023 |
| Skjerven Skog Holding AS | Wholesale & retail | 2007 |
| Sko-Huuse AS | Wholesale & retail | 1978 |
| Skog Holding AS | Manufacturing | 2004 |
| Skogli Invest AS | Financial services | 2017 |
| Skoglund Ventilasjon Og Blikkenslagerverksted AS | Construction | 2006 |
| Skoglund- Transport AS | Transport & logistics | 2019 |
| Skolelyd AS | Wholesale & retail | 2019 |
| Skolevegen 13 AS | Real estate | 2015 |
| Skomakermester Våge AS | Other services | 2015 |
| Skulevegen 7 Leira AS | Real estate | 2021 |
| Slice Holding AS | | 2023 |
| Slitu Butikkeiendom AS | Real estate | 2017 |
| Slots AS | Health & social care | 2021 |
| Slåbrok AS | Real estate | 2020 |
| Sm.Md AS | Health & social care | 2023 |
| Smakfullt Fisk Og Delikatesser AS | Wholesale & retail | 2011 |
| Smart Medical Discovery AS | Professional & scientific | 2025 |
| Smedsrud Holding AS | | 2021 |
| Smil Aviation AS | Wholesale & retail | 2025 |
| SML Helse AS | Health & social care | 2021 |
| Smørvika Utvikling AS | Real estate | 2017 |
| SN Utvikling AS | Real estate | 2016 |
| Snabela AS | Real estate | 2007 |
| Snadderhjørnet Kiosk AS | Wholesale & retail | 2025 |
| Snap Holding AS | | 2022 |
| Snekkeriet Gjøvik Ans | Construction | 2002 |
| Snekkerkameratene AS | Construction | 2025 |
| Snertin Holding AS | Real estate | 2024 |
| Snowflake Invest AS | Manufacturing | 2011 |
| Snøugle AS | Professional & scientific | 2022 |
| Sognsveien 66 Butikkeiendom AS | Real estate | 2020 |
| Sogstad AS | Real estate | 2006 |