| Severin Kjærsvei 45 AS | Real estate | 2008 |
| SG Bidco AS | Information & communication | 2015 |
| SG Teknikk AS | Wholesale & retail | 2024 |
| Shifftmaker AS | Professional & scientific | 2024 |
| Ship Contact AS | Real estate | 2007 |
| Ship Innovation AS | Professional & scientific | 2013 |
| Sicotronic Norge AS | Wholesale & retail | 2023 |
| Siempre AS | Financial services | 2014 |
| Siga Holding AS | Professional & scientific | 2014 |
| Sik Invest AS | | 2021 |
| Sikkerhetskompaniet AS | Construction | 2007 |
| Sikre Råd AS | Professional & scientific | 2022 |
| Silje Natland Holding AS | | 2024 |
| Siljudalen Agentur AS | Wholesale & retail | 2015 |
| Sima Global Holding AS | Real estate | 2005 |
| Sima Nor AS | Wholesale & retail | 1999 |
| Simitu AS | Education | 2021 |
| Simply Group AS | Real estate | 1998 |
| Simply Invest AS | Real estate | 2014 |
| SIMPLYGR8 AS | Professional & scientific | 2018 |
| Sinergi AS | Information & communication | 2023 |
| Singh Property AS | Real estate | 2024 |
| Single Office AS | Real estate | 2003 |
| Sirius C AS | Real estate | 2002 |
| Sirras AS | | 2006 |
| Siv Ing Øyvind Stokke AS | Professional & scientific | 2010 |
| Sivilarkitekt Nils-Jacob Lugg AS | Professional & scientific | 1998 |
| Sjåfør Og Personell Utleie AS | Transport & logistics | 2017 |
| Sjøbadet AS | Arts & recreation | 2020 |
| Sjøboden Drift AS | Arts & recreation | 2012 |
| Skadedyrbutikken AS | Wholesale & retail | 2011 |
| Skadedyrgrossisten AS | Wholesale & retail | 2026 |
| Skagen Forvaltning AS | Real estate | 2013 |
| Skagerak International School, Tønsberg AS | Education | 2018 |
| Skatvedt AS | Real estate | 2018 |
| Skauen AS | Wholesale & retail | 2022 |
| Skauen Hvitevarer Tønsberg AS | Wholesale & retail | 2015 |
| Skeidar Tønsberg AS | Wholesale & retail | 1996 |
| Skibsgateplassen Invest AS | Real estate | 2006 |
| Skilsø Eiendom AS | Real estate | 1992 |
| Skippergata 6 AS | Real estate | 2019 |
| Skjelbred Brands AS | Wholesale & retail | 2025 |
| Skjelde Holding AS | | 2025 |
| Skjelland AS | Wholesale & retail | 1956 |
| Skjelland Group AS | Wholesale & retail | 2016 |
| Skjelland Invest AS | Wholesale & retail | 1995 |
| Skjerve & Jahnsen Invest Ans | | 1991 |
| Skjervekiosken AS | Hospitality | 2026 |
| Skjevika Eiendomsutvikling AS | Real estate | 2018 |
| Skjold & Sønn AS | Real estate | 2005 |
| Skjærset Consulting AS | Information & communication | 2024 |
| Skog Arkitekter AS | Professional & scientific | 2019 |
| Skolerom AS | Information & communication | 2023 |
| Skoleveien Bolig AS | Real estate | 2017 |
| Skrida AS | Professional & scientific | 2022 |
| Sky Design AS | Wholesale & retail | 1994 |
| Sky Talk AS | Professional & scientific | 2012 |
| Skya Markedsføring AS | Professional & scientific | 2020 |
| Skya Regnskap AS | Professional & scientific | 2016 |
| SKYA24 Holding AS | Real estate | 2021 |
| Skøyteshop AS | Wholesale & retail | 2018 |
| Slagenveien Tønsberg Apotek AS | Wholesale & retail | 2025 |
| Slim Holding AS | Professional & scientific | 2021 |
| Slim Invest AS | | 2023 |
| Slottsfjell Forsikring AS | Financial services | 1995 |
| Slottsfjell Gulvteknikk AS | Construction | 2023 |
| Slottsfjellfestivalen AS | Arts & recreation | 2010 |
| Slottsfjellskolen AS | Real estate | 2023 |
| Smars AS | | 2025 |
| Smart Rør AS | Construction | 2019 |
| Smartcode AS | Information & communication | 2015 |
| Smarttekenergi AS | Professional & scientific | 2014 |
| SMD Invest AS | | 2021 |
| Sme Eiendom Ans | Real estate | 1999 |
| Smidsrød Eiendom AS | Real estate | 2021 |
| Smidsrødveien 2 B AS | Real estate | 2013 |
| Smidsrødveien 4A AS | Real estate | 2012 |
| Smidsrødveien 4C AS | Real estate | 2022 |
| Smidsrødveien 6 AS | Real estate | 2022 |
| Smith Larsen Consulting AS | Professional & scientific | 1996 |
| Smith Petersensgate 10 AS | Real estate | 2016 |
| SMK Holding AS | Real estate | 2012 |
| Smørepunkt Tønsberg AS | Other services | 2025 |
| SN Holding AS | Real estate | 2018 |
| Sofies Villa Tønsberg AS | Wholesale & retail | 2014 |
| Solberg Byggservice AS | Construction | 2025 |
| Solberg Eiendomsutvikling AS | Real estate | 2007 |
| SOLBERG34 Consulting AS | Professional & scientific | 2020 |
| Sole Drift AS | Hospitality | 2012 |
| Solhagen Eiendom AS | Real estate | 2013 |
| Solheden Holding AS | | 2005 |
| Solheim & Co Invest AS | | 2026 |
| Solkilen Terrasse AS | Real estate | 2017 |
| Solo Bygg & Entreprenør AS | Construction | 2026 |
| Solpumpa AS | Manufacturing | 2017 |
| Solum & Sønn Transport AS | Transport & logistics | 1994 |
| Solvanglia Garasjeanlegg SA | Households | 1985 |
| Solåsen Re AS | Real estate | 2015 |
| Solåshagen AS | Construction | 2018 |
| Somjit Thaimassasje AS | Other services | 2023 |