| Mymechanic Verksted AS | Other services | 2025 |
| Målsneskaia AS | Real estate | 2011 |
| Møbelringen Studio Tiller AS | Wholesale & retail | 2025 |
| N-Holding AS | Financial services | 2005 |
| Naboen Pizza & Grill AS | Hospitality | 2011 |
| Naits Holding AS | | 2024 |
| Najs AS | Professional & scientific | 2020 |
| Nano Detailing AS | Other services | 2020 |
| Nardoveien 4 AS | Real estate | 2019 |
| Navartech AS | Professional & scientific | 2005 |
| NB Explore AS | Information & communication | 2024 |
| Nensetjordet Eiendom AS | Real estate | 2019 |
| Neontex AS | Manufacturing | 1985 |
| Nesset Flytting AS | Administrative & support | 2020 |
| Nettbutikkdrift AS | Information & communication | 2017 |
| Netzero Ventures AS | | 2025 |
| Nidaros Bygg & Utleie AS | Real estate | 2023 |
| Nidaros Mur&Flis AS | Construction | 2026 |
| Nidarvoll Eiendom AS | Real estate | 2024 |
| Nilsen Tak AS | Construction | 2024 |
| Ninjaponni Invest AS | | 2021 |
| No Limits Holding AS | Wholesale & retail | 2019 |
| Nordic Lift AS | Wholesale & retail | 2007 |
| Nordic Performance AS | Health & social care | 2020 |
| Nordisk Dansegalla AS | Arts & recreation | 2020 |
| Nordiska Va Teknik AS | Real estate | 2023 |
| Nordre Trondskogen AS | Real estate | 2026 |
| Norgesgruppen Eiendom Midt-Norge AS | Real estate | 1984 |
| Norgesgruppen Midt-Norge AS | Real estate | 1964 |
| NORINVEST1 AS | Real estate | 2012 |
| NORINVEST2 AS | Real estate | 2012 |
| NORINVEST3 AS | Real estate | 2012 |
| Norkapital Holding AS | | 2008 |
| Norluft AS | Wholesale & retail | 1985 |
| Norvegr Down Duvets AS | Manufacturing | 2002 |
| NRS Norge AS | Administrative & support | 1997 |
| Nt&D Trondheim AS | Information & communication | 2023 |
| NTN Shop AS | Wholesale & retail | 1997 |
| Nummer 11 AS | Professional & scientific | 2025 |
| NW Bakken Eiendom AS | Administrative & support | 2025 |
| NW Bakken Holding AS | | 2025 |
| Ny Era AS | Real estate | 2021 |
| Nye Car Craft Eiendom AS | Real estate | 2013 |
| Nyhusvegen AS | Real estate | 2017 |
| Næringspark Syd Trondheim AS | Real estate | 2011 |
| O. a. Røed - Salg & Konsulenttjenester AS | Wholesale & retail | 2024 |
| O.Løkken A/S | Construction | 1982 |
| Oafuruhaug AS | | 2023 |
| Odd Kolstad AS | Wholesale & retail | 2013 |
| Odd Langdalen Frukt Og Grønt Avd Trondheim AS | Wholesale & retail | 2007 |
| Oi Hår Og Velværesenter AS | Other services | 2004 |
| Ok Økonomi AS | Professional & scientific | 2015 |
| Ole Dragsten Invest AS | Financial services | 2005 |
| Olseb AS | Hospitality | 2024 |
| Olvard Holding AS | | 2008 |
| Opalia Trondheim AS | Health & social care | 2019 |
| Opplæringskontoret for Transport Og Logistikk Trøndelag SA | Education | 1995 |
| Opstad Konsult AS | Professional & scientific | 1991 |
| Optimum Regnskap AS | Professional & scientific | 2015 |
| Optituning AS | Other services | 2011 |
| Optituning Trondheim AS | Information & communication | 2020 |
| Orkla Holding AS | Professional & scientific | 2003 |
| Orkla Regnskap AS | Professional & scientific | 2012 |
| Orkla Revisjon AS | Professional & scientific | 2020 |
| Ottos Holding AS | Professional & scientific | 2022 |
| Otts AS | Transport & logistics | 2011 |
| Overaae AS | Wholesale & retail | 1984 |
| Overaae Holding AS | | 1996 |
| Owne AS | Professional & scientific | 2024 |
| Pappas Kjøkken AS | Hospitality | 2023 |
| Park Lian AS | | 2025 |
| Parksystemer AS | Professional & scientific | 2025 |
| Partnerdata AS | Information & communication | 2002 |
| PB Holding AS | Financial services | 2010 |
| Peakload Technologies AS | Professional & scientific | 2017 |
| Pearl of India AS | Hospitality | 2025 |
| Peis Og Varme Trondheim AS | Construction | 2020 |
| Persson Norge AS | Real estate | 1973 |
| PN Eiendom Nord AS | Real estate | 2005 |
| PNH AS | Arts & recreation | 2015 |
| Podpal Games AS | Information & communication | 2017 |
| Pokeshop Da | Wholesale & retail | 2023 |
| Polar Kuldeservice AS | Construction | 2011 |
| Polardrikk Trondheim AS | Wholesale & retail | 2016 |
| Premium Living AS | | 2018 |
| Pro Integrated Management AS | Professional & scientific | 2012 |
| Produksjon 24 AS | Manufacturing | 2023 |
| Profila AS | Professional & scientific | 2009 |
| Profila Eiendom AS | Professional & scientific | 2014 |
| Prosjektstyring Midt AS | Professional & scientific | 2015 |
| Protek VVS AS | Construction | 2024 |
| Proxycom AS | Information & communication | 1997 |
| PS Serigrafi AS | Manufacturing | 1997 |
| Quality Hotel Panorama AS | Hospitality | 1992 |
| R.L. Holding AS | Real estate | 2011 |
| Railgun Entertainment AS | Information & communication | 2022 |
| Ramox Eiendom Tiller AS | Real estate | 2012 |
| Ramox Invest AS | Real estate | 2005 |
| Raptor Holding AS | Financial services | 2016 |
| Raye Holding AS | | 2023 |