| Sealit AS | Professional & scientific | 2023 |
| Searcular AS | Information & communication | 2018 |
| Seas of Norway AS | Professional & scientific | 2019 |
| SEASONS4ALL AS | Wholesale & retail | 2013 |
| Seawing Capital AS | Professional & scientific | 2011 |
| Seb Services AS | Professional & scientific | 2009 |
| Sebjørnsrud Gård AS | Transport & logistics | 2025 |
| Sebrusletto AS | Arts & recreation | 2026 |
| Segvent AS | Wholesale & retail | 2015 |
| Seh Capital AS | | 2025 |
| Seil Eiendomsmegling AS | Real estate | 2017 |
| Seilø AS | Real estate | 2017 |
| Selan AS | | 2017 |
| Selskap 1 AS | Education | 2018 |
| Selvanraa AS | Professional & scientific | 2006 |
| Sem Barnehage SA | Education | 1990 |
| Sem Bruk AS | Administrative & support | 1996 |
| Sem Bruk Eiendom AS | Real estate | 1974 |
| Semy AS | Real estate | 2007 |
| Semy Felleskost AS | Real estate | 2025 |
| Seniorveien AS | Professional & scientific | 2026 |
| Sensee AS | Information & communication | 2014 |
| Senses AS | Other services | 2008 |
| Sentient Futures Holding AS | Information & communication | 2024 |
| Sepia AS | Health & social care | 2012 |
| Sesilie Smørholm Holding AS | Financial services | 2016 |
| Setim-Services | Administrative & support | 2016 |
| SG Fysio Og Manuellterapi AS | Health & social care | 2018 |
| SGP Holding AS | | 2005 |
| Sherbourne Invest AS | | 2026 |
| SHK Consulting AS | Professional & scientific | 2025 |
| Shy 214 Holding AS | | 2023 |
| Sich Holding AS | Real estate | 2007 |
| Signed by Sensa AS | Professional & scientific | 2015 |
| Sigurd Fossli AS | Construction | 1971 |
| Siin Holding AS | | 2020 |
| Silfr AS | Information & communication | 2025 |
| Siljan Invest AS | Real estate | 2014 |
| Silvestris AS | | 2021 |
| Simac AS | Wholesale & retail | 2005 |
| Simon Dahl AS | Professional & scientific | 2007 |
| Simonin Holding AS | | 2023 |
| Sinmar AS | Financial services | 2008 |
| Siolill AS | Professional & scientific | 2008 |
| Sist Invest AS | Real estate | 2021 |
| Siste Soldager Kapital AS | | 2026 |
| Siv Ing Ingar Brauti AS | Professional & scientific | 1994 |
| Sivcom AS | Professional & scientific | 2019 |
| Sivilingeniør Geir a Hilde AS | Professional & scientific | 1995 |
| Sivilingeniør Øyvind N. Nielsen AS | Professional & scientific | 1987 |
| Sj-Holding AS | Professional & scientific | 2010 |
| SJB AS | | 2025 |
| SJB Sven Johansson Anlaggning Aktiebolag | Administrative & support | 1997 |
| Sjel Holding AS | | 2024 |
| Sjo Kommunikasjon AS | Professional & scientific | 1986 |
| Sjuan AS | Professional & scientific | 2025 |
| Sjøheim Invest AS | | 2023 |
| Sk-Holding AS | Financial services | 2014 |
| Skaaret Agentur AS | Wholesale & retail | 1988 |
| Skaaret Eiendom AS | Real estate | 1993 |
| Skaaret Holding AS | Real estate | 1967 |
| Skaaret Landskap AS | Administrative & support | 1994 |
| Skaaret Management Group AS | Arts & recreation | 2004 |
| Skallum Utbygging AS | Real estate | 2014 |
| Skatek AS | Professional & scientific | 2021 |
| Skattekart AS | | 2023 |
| Skattekisten AS | Real estate | 2019 |
| Skaugum Invest AS | Real estate | 2005 |
| Skaumann AS | Financial services | 2013 |
| Skien Industribygg AS | Financial services | 2018 |
| Skinvest AS | Financial services | 2012 |
| Skiplukkern AS | Wholesale & retail | 2020 |
| Skjefstad Invest AS | Professional & scientific | 2023 |
| Skjellerfjellet AS | | 2022 |
| Skjærlagsåsen Utvikling AS | Real estate | 2018 |
| Skogstjerne AS | | 2020 |
| Skoja Da | Wholesale & retail | 2002 |
| Skramstadkvartalet AS | Real estate | 2017 |
| Skuncke Consulting AS | Professional & scientific | 2013 |
| Skuncke Works AS | | 2024 |
| Skytterveien 200 AS | Real estate | 1985 |
| SL Konsult AS | Professional & scientific | 2015 |
| Slettebakk Holding AS | | 2026 |
| Slåvika AS | Professional & scientific | 2020 |
| Smakslykke Asker AS | Wholesale & retail | 2025 |
| Smaragthi Fashion | Wholesale & retail | 1986 |
| Smart Life AS | Wholesale & retail | 2023 |
| Smart Skap AS | Wholesale & retail | 2025 |
| Smartco AS | | 2002 |
| Smarte Produkt AS | Wholesale & retail | 2025 |
| Smartere IT Holding AS | | 2022 |
| Smartmat Da | Wholesale & retail | 2000 |
| SMB Engros AS | Manufacturing | 2025 |
| Smykkefeber AS | Wholesale & retail | 2024 |
| Småjobber- Asker AS | Construction | 2026 |
| Snake Oil Holdings AS | Information & communication | 2019 |
| Snaxynator Holding AS | Health & social care | 2024 |
| Snersrud & Pedersen AS | Construction | 2019 |
| Snoox Studios AS | Information & communication | 2024 |
| Soaa Holding AS | Professional & scientific | 2022 |