| Sirdal Entreprenør Service AS | Construction | 2026 |
| Sirdal Fisk AS | Agriculture & fishing | 2015 |
| Sirdal Fisk Asset AS | Administrative & support | 2022 |
| Sirdal Handlaft AS | Construction | 1997 |
| Sirdal Huskyfarm AS | Administrative & support | 2010 |
| Sirdal Hytter Og Hus AS | Construction | 2002 |
| Sirdal Hyttetjenester AS | Administrative & support | 2021 |
| Sirdal Landbruksverksted AS | Manufacturing | 2012 |
| Sirdal Mat Og Brygghus AS | Hospitality | 2016 |
| Sirdal Regnskapslag SA | Professional & scientific | 1971 |
| Sirdal Sag AS | Manufacturing | 2001 |
| Sirdal Servering AS | Hospitality | 2026 |
| Sirdal Stun AS | Transport & logistics | 2022 |
| Sirdal Transport Ans | Transport & logistics | 1993 |
| Sirdal Transportservice AS | Transport & logistics | 2004 |
| Sirdalmedia AS | Information & communication | 2024 |
| Sirdalsbussen AS | Transport & logistics | 2011 |
| Sirdalsmaleren AS | Construction | 2013 |
| Sirdalsmat SA | Other services | 2013 |
| Sirdex AS | Wholesale & retail | 2026 |
| Siv Ing Per Olav Haughom AS | Professional & scientific | 1998 |
| Skeie Maskin AS | Construction | 2003 |
| Skretting Flis AS | Construction | 2014 |
| Skreådalen Beitelag SA | Agriculture & fishing | 1977 |
| Slice Sirdal AS | Hospitality | 2026 |
| Solheim Utbyggingsselskap AS | Real estate | 2005 |
| Solå-Dalen Beitelag | Agriculture & fishing | 1998 |
| Spectacular Norway AS | Professional & scientific | 2024 |
| Steis Eiendom AS | Manufacturing | 1997 |
| Steis Mekaniske Verksted AS | Manufacturing | 1996 |
| Steis Solutions AS | Professional & scientific | 2020 |
| Strandbergmyra Fjellgård AS | Construction | 2018 |
| SV Drift Og Catering AS | Hospitality | 2021 |
| SVB Gruppen AS | Construction | 2019 |
| SVB Infra AS | Wholesale & retail | 2026 |
| Svb-Eiendom AS | Real estate | 2020 |
| T O Bildeler Og Utleie Da | Wholesale & retail | 2001 |
| Terje Moen Holding AS | Financial services | 2012 |
| Thermofly AS | Professional & scientific | 2023 |
| Thin AS | Information & communication | 2008 |
| Tonstad Autosenter AS | Other services | 2023 |
| Tonstad Bakeri AS | Manufacturing | 2000 |
| Tonstad Invest AS | | 2023 |
| Tonstad Kolonial AS | Wholesale & retail | 2023 |
| Tonstad Maskinfabrikk AS | Real estate | 1983 |
| Tonstad Motorservice AS | Wholesale & retail | 2010 |
| Tonstad Park AS | Real estate | 2025 |
| Tonstad Taxi AS | Transport & logistics | 2006 |
| Tonstad Utvikling AS | Real estate | 2007 |
| Tonstad Utvikling Holding AS | Real estate | 2024 |
| Tonstadli Hotell AS | Hospitality | 2014 |
| Tore Morten Ousdal AS | Construction | 2013 |
| Turbineco AS | Professional & scientific | 2021 |
| Tveit Og Tjomlid Maskin AS | Construction | 2001 |
| Tyriskogen AS | Construction | 2015 |
| Vannveien Service AS | Professional & scientific | 2013 |
| Vidvanke AS | Professional & scientific | 2016 |
| Vindelev AS | Health & social care | 2021 |
| Øksendal Revisjon AS | Professional & scientific | 2011 |