| Oscar Nissensgate 4-6 AS | Real estate | 2006 |
| Oskar Johansen AS | Construction | 1994 |
| Otjl Eiendom AS | Real estate | 2023 |
| Otjl Invest AS | Real estate | 2012 |
| Otters Bil AS | Wholesale & retail | 2022 |
| Otto AS | Real estate | 2000 |
| Out of Home AS | Wholesale & retail | 2016 |
| Ovarn AS | Real estate | 2025 |
| Pah Holding AS | | 2021 |
| Paraveka AS | Other services | 2024 |
| Peis Og Pipefag AS | Construction | 2016 |
| Per Thorstensen Konsult AS | Professional & scientific | 2026 |
| Perfekt Effekt Service AS | Administrative & support | 2018 |
| Pilot Pier AS | Real estate | 2018 |
| Pink Tigers AS | Other services | 2018 |
| Pladsen Invest AS | Hospitality | 2020 |
| Pos Mat Og Fritid AS | Hospitality | 2024 |
| Poui Invest AS | | 2020 |
| Pre-Camp AS | Construction | 2022 |
| Precamp AS | Construction | 2011 |
| Predas Verksted Da | Wholesale & retail | 2012 |
| Preg Barnehager Tinnesmoen AS | Education | 2022 |
| Prenet AS | Information & communication | 2025 |
| Primaktiv AS | | 2020 |
| Prime Holding AS | Professional & scientific | 2014 |
| Proffin AS | Wholesale & retail | 2023 |
| Project Solutions AS | Professional & scientific | 2019 |
| Prosjekt Service Invest AS | | 1993 |
| Prosjekt Service Invest Holding AS | | 2005 |
| Pureinvest AS | | 2021 |
| Quality Nest AS | Information & communication | 2016 |
| Quicklymade AS | Manufacturing | 2013 |
| R&N Holding AS | Construction | 2022 |
| R-Maja Ou | Construction | 2006 |
| R.O.P.E.S AS | Arts & recreation | 2006 |
| Radio Notodden AS | | 2025 |
| Radix Equity AS | | 2017 |
| Railroad AS | Wholesale & retail | 2016 |
| Ramberghjørnet Eiendom AS | Real estate | 2016 |
| Ramberghjørnet Holding AS | Real estate | 2016 |
| Ramsåe Kraft AS | Energy | 2022 |
| Rao Marketing AS | Professional & scientific | 2025 |
| Regnskapskontoret AS | Information & communication | 1982 |
| Rei Invest AS | Financial services | 2005 |
| Rekaa Sag & Høvleri Ans | Manufacturing | 1994 |
| Rekåa Kraftverk AS | Energy | 2009 |
| Rekåvegen SA | Real estate | 1982 |
| Remida AS | Education | 2003 |
| Returbukk Holding AS | | 2023 |
| Revisorteam AS | Professional & scientific | 1985 |
| RF Management AS | Professional & scientific | 2019 |
| Richter Holding AS | | 2025 |
| Rie Telemark AS | Professional & scientific | 2013 |
| Rinde Bil AS | Wholesale & retail | 2022 |
| Rindo AS | Real estate | 2022 |
| Roar Aas Maskin AS | Construction | 2024 |
| Robertsen & Solberg Bilsenter AS | Wholesale & retail | 1986 |
| Robust Kropp Og Helse AS | Health & social care | 2022 |
| Rocstar Holding AS | Professional & scientific | 2021 |
| Rofono AS | Health & social care | 2002 |
| Roland Transport AS | Transport & logistics | 2013 |
| ROM116 AS | Real estate | 2021 |
| Royal AS | Wholesale & retail | 2015 |
| RR Graving Og Utleie Da | Construction | 2007 |
| Runar Bakken AS | Transport & logistics | 2005 |
| Runarson AS | | 2020 |
| Rygi Grendeveg SA | Real estate | 2022 |
| Rødmyrlia 39 AS | Real estate | 2012 |
| Rødmyrlia Eiendom AS | Real estate | 1995 |
| Rørlegger Kongsvold AS | Construction | 2023 |
| Rørleggerservice Notodden AS | Construction | 2016 |
| S & V Automobilprodukter AS | Wholesale & retail | 1989 |
| S.A Service AS | Administrative & support | 2024 |
| S38 Consulting AS | Professional & scientific | 2022 |
| Sandvik Transport AS | Wholesale & retail | 2010 |
| Sangerheimen AS | Real estate | 2024 |
| Sauarlia Invest AS | Real estate | 1996 |
| SB Anlegg AS | Professional & scientific | 2021 |
| Scandicamp AS | Wholesale & retail | 2014 |
| Schia Eiendom AS | Real estate | 2010 |
| Schia Holding AS | Real estate | 2011 |
| Seljord Bergestig Holding AS | | 2023 |
| Semsvegen 41D AS | Real estate | 2025 |
| Semsvegen 80 AS | Real estate | 2012 |
| Semsvegen Eiendom AS | Real estate | 1991 |
| Semsveien 48 B AS | Real estate | 2004 |
| Senter for Global Og Komparativ Idéhistorie SA | Professional & scientific | 2015 |
| Sentrumslegene I Notodden Da | Health & social care | 2015 |
| Servicepartner Notodden AS | Construction | 2001 |
| SH Square AS | Professional & scientific | 2022 |
| Siba AS | | 2020 |
| Sikte Landmåling AS | Professional & scientific | 2018 |
| SINGLE4YOU Da | Other services | 2004 |
| Sjova AS | Arts & recreation | 2021 |
| Skatter AS | Real estate | 2024 |
| Skaue AS | Health & social care | 2016 |
| Skildrud Eiendom AS | Real estate | 2020 |
| Skildrud Holding AS | Real estate | 2020 |
| Skrivar Wessels Eiendom AS | Real estate | 2015 |
| Skyhauk AS | Real estate | 2011 |