| Sarp Kraftstasjon AS | Energy | 1987 |
| Sendola AS | Information & communication | 2024 |
| Sento AS | Wholesale & retail | 2006 |
| Sentrumsgården Askim AS | Real estate | 2010 |
| SH Musikk AS | Arts & recreation | 2020 |
| Siam Takeaway Mat AS | Hospitality | 2025 |
| Simic Invest AS | Financial services | 2021 |
| Sira Sigurdsgate 24 AS | Real estate | 2021 |
| SK Tungtransport Ans | Transport & logistics | 2006 |
| Skandun AS | Wholesale & retail | 2005 |
| Skave AS | Construction | 2020 |
| Skiltmakeren AS | Professional & scientific | 2024 |
| Skiltmakeren Holding AS | | 1994 |
| Skoglund Eiendomsutvikling AS | Real estate | 2019 |
| Skogveien 22 AS | Real estate | 2023 |
| Skolegata 16 AS | Real estate | 2024 |
| Skolegata Askim AS | | 2018 |
| Smaalenene Eiendomsmegling AS | Real estate | 2022 |
| Smaalenene Holding AS | Hospitality | 2005 |
| Smaalenene Medier AS | Information & communication | 1997 |
| Smart Lager AS | Transport & logistics | 2023 |
| Smart Supply AS | Wholesale & retail | 2007 |
| Smash Buddies AS | Hospitality | 2023 |
| Smykkebygg AS | Construction | 2018 |
| Snack House AS | Hospitality | 2025 |
| Snø & Vedlikehold AS | Administrative & support | 2017 |
| Sohal AS | | 2025 |
| Solli & Hoff Oppmåling AS | Professional & scientific | 1969 |
| Sopel Holding AS | | 2024 |
| Spirgis AS | Wholesale & retail | 2021 |
| Spiss AS | Education | 2024 |
| Spjudvik Invest AS | Construction | 2014 |
| Spjudvik Rør AS | Construction | 2016 |
| Sprett Trampolinepark Askim AS | Arts & recreation | 2018 |
| Spring Invest AS | Wholesale & retail | 2005 |
| Spydeberg - Stasjonsgata 30 AS | Real estate | 2025 |
| Spydeberg Lager AS | Real estate | 2021 |
| Spydeberg Vekst AS | Real estate | 1984 |
| Stah Invest AS | | 2026 |
| Stasjonsmester Frosts Gate 2 AS | Real estate | 2025 |
| Steen Catering AS | Hospitality | 2013 |
| Stegra Entreprenør AS | Construction | 2001 |
| Stordahls Invest AS | | 2024 |
| Stordahls Ventilasjon AS | Construction | 2025 |
| Storgt. 7 Askim AS | Real estate | 2016 |
| Stubbeskogen Naturbarnehage AS | Education | 2011 |
| Støtengruppen AS | Administrative & support | 2006 |
| Superday Group AS | Arts & recreation | 2014 |
| Supreme Invest AS | Information & communication | 2017 |
| Sushitake AS | Hospitality | 2019 |
| Svarstad Eiendom AS | Real estate | 2020 |
| Svarstad Holding AS | Real estate | 2005 |
| Sveens Rørleggerservice AS | Real estate | 2000 |
| Sydengen Elgjaktlag SA | Agriculture & fishing | 2019 |
| Sydengen Invest | | 2024 |
| Sylliaas Invest AS | Information & communication | 2023 |
| Synssenteret Askim Holding AS | | 2005 |
| Synssenteret DD Askim AS | | 2023 |
| Synssenteret Ep AS | | 2022 |
| Synssenteret JRK Askim AS | Wholesale & retail | 2006 |
| Syverud VVS AS | Construction | 2023 |
| Søhoel Boligutvikling AS | Construction | 1999 |
| Søhoel Eiendom Og Byggservice AS | Construction | 1999 |
| Søhoel Invest AS | Real estate | 2004 |
| Søhoel Næring AS | Real estate | 2007 |
| Sørbråten & Strand's Budservice Da | Transport & logistics | 2013 |
| Sørby Eiendom Og Drift AS | Real estate | 2001 |
| Sørby Trafikkskole Drift AS | Education | 2020 |
| Sørlie El. Installasjon AS | Construction | 2013 |
| Søvikholding AS | Real estate | 2020 |
| T & T Service Partner AS | Construction | 2021 |
| T Key-Kristiansen Kontorservice AS | Wholesale & retail | 1984 |
| Ta Bo Holding AS | | 2019 |
| Ta VVS AS | Construction | 2024 |
| Tak Og Membran AS | Construction | 1993 |
| Tak Og Tre AS | Construction | 2026 |
| Tako-Invest AS | Real estate | 2004 |
| Tales Invest AS | | 2020 |
| Tankservice AS | Transport & logistics | 1990 |
| Taosoft AS | | 2026 |
| Taras Pizza & Kebab AS | Hospitality | 2018 |
| Tarass Rozko Vent AS | Construction | 2026 |
| TB Equestrian AS | Agriculture & fishing | 2022 |
| Te Sø Holding AS | Education | 2012 |
| Team Take Off Da | Administrative & support | 2003 |
| Team Trafikkskole AS | Education | 1994 |
| Tebo 1 AS | Real estate | 2015 |
| Tebo Senteret AS | Real estate | 2015 |
| Tec AS | Real estate | 2005 |
| Tech-Rens AS | Administrative & support | 2026 |
| Technomedics Norge AS | Wholesale & retail | 2003 |
| Techrens AS | Administrative & support | 2021 |
| Teigen Media AS | Professional & scientific | 2024 |
| Teklay AS | Wholesale & retail | 2023 |
| Tele Site AS | Information & communication | 2023 |
| Teleagaos AS | Wholesale & retail | 2017 |
| Tendon Klinikk AS | Health & social care | 2013 |
| Thermo Tours AS | Administrative & support | 2010 |
| Thorkine AS | Information & communication | 1996 |
| THV Rom AS | Wholesale & retail | 1989 |