| Idungården Legesenter Da | Health & social care | 2001 |
| Idégården AS | Real estate | 2019 |
| Idéhus Trondheim AS | Construction | 2003 |
| Iesjohka AS | | 2020 |
| Ifix AS | Administrative & support | 2013 |
| Iform Bygg AS | Construction | 2012 |
| Ig Drift AS | Real estate | 2012 |
| Igaming Consultant AS | Information & communication | 2025 |
| Igb Invest AS | | 2022 |
| Igelfjell AS | | 2025 |
| Igelkott Holding AS | | 2025 |
| Igesund Software Consulting AS | Information & communication | 2015 |
| Ignia AS | Professional & scientific | 2023 |
| Iherdig AS | Wholesale & retail | 2018 |
| Ihv Invest AS | | 2022 |
| Ik Invest AS | Real estate | 2006 |
| Ikaros AS | Real estate | 2025 |
| Ikos Barbershop AS | Other services | 2024 |
| Il Futuro Invest AS | | 2025 |
| Il Kuranto AS | Real estate | 2025 |
| Il.Fornaio AS | Hospitality | 2023 |
| Ila Bokholderi AS | Professional & scientific | 1989 |
| Ila Bokholderi Eiendom AS | Real estate | 2001 |
| Ila Boligutleie AS | Real estate | 2017 |
| Ila Bygg AS | Real estate | 2006 |
| Ila Bygginvest AS | Real estate | 2006 |
| Ila Development AS | Real estate | 2017 |
| Ila Eiendom AS | Real estate | 1987 |
| Ila Fiskemottak AS | Administrative & support | 2010 |
| Ila Holding AS | Real estate | 2005 |
| Ila Invest Holding AS | Real estate | 2016 |
| Ila Legesenter Da | Health & social care | 2013 |
| Ila Legetjenester AS | Health & social care | 2022 |
| Ila Pizza Restaurant Og Bar Da | Hospitality | 2005 |
| Ila Trafikkskole AS | Education | 2013 |
| Ilevollen 3C AS | Real estate | 2025 |
| Ilevollen 3F AS | Real estate | 2025 |
| Ilevollen Dagligvare AS | Wholesale & retail | 2016 |
| Ilevollen Fysioterapi Og Trening AS | Health & social care | 2019 |
| Illumie AS | Information & communication | 2025 |
| Illusion Invest AS | | 2019 |
| Ilsvika Garden AS | Other services | 2018 |
| Ilsvika Restaurant AS | Hospitality | 2017 |
| Im Holding AS | Professional & scientific | 2010 |
| Im Malvik AS | Professional & scientific | 2013 |
| Image Design Trondheim Ans | Wholesale & retail | 1996 |
| Imaginer AS | Professional & scientific | 2012 |
| Imali AS | Hospitality | 2018 |
| Imisu AS | Education | 2006 |
| Imko AS | | 2019 |
| Immer AS | Professional & scientific | 2014 |
| Immobilier AS | Real estate | 2012 |
| Impact Motion AS | Professional & scientific | 2025 |
| Impera AS | Wholesale & retail | 2023 |
| Implisitt AS | Professional & scientific | 2025 |
| Importa AS | Real estate | 2021 |
| Impressario AS | Professional & scientific | 2021 |
| Improlog AS | Wholesale & retail | 2022 |
| Impulse Treningssenter AS | Arts & recreation | 2014 |
| Imunnen AS | Health & social care | 2020 |
| In-Motion Technologies AS | Information & communication | 2023 |
| IN5 Real Estate AS | Real estate | 2004 |
| Ina Holding AS | Wholesale & retail | 2022 |
| Inadvis AS | Professional & scientific | 2024 |
| Inaq AS | Professional & scientific | 2020 |
| Inbovi AS | Information & communication | 2015 |
| Inconspicuous AS | Information & communication | 2013 |
| Indago Consult AS | Professional & scientific | 2026 |
| Index Holding AS | Information & communication | 2005 |
| Indoor Golf Trondheim AS | Arts & recreation | 2024 |
| Indusenz AS | Information & communication | 2018 |
| Industri Partner AS | Professional & scientific | 1994 |
| Industriinvest I AS | Real estate | 2006 |
| Industrious AS | Information & communication | 2026 |
| Industriparken AS | Manufacturing | 2023 |
| Industriparken Eiendom AS | Real estate | 2008 |
| Industriveien 3-5 AS | Real estate | 2011 |
| Industriveien 31 Holding AS | Real estate | 2021 |
| Industriveien 59 AS | Real estate | 2006 |
| Industriveien 67 AS | Real estate | 2021 |
| Industriveien 7 Eiendom AS | Real estate | 1953 |
| Industry Solution AS | Information & communication | 2025 |
| Infiniwell AS | Information & communication | 2018 |
| Infotrend Estate AS | Real estate | 1999 |
| Ing a R Berdal AS | | 2023 |
| Ing. Torstein Ryghaug A.S | Professional & scientific | 1988 |
| Ing. Vijo Holdingselskap AS | | 2026 |
| Inge Haugan Bygg AS | Construction | 2004 |
| Inge Krokanns Veg 14 AS | Real estate | 2013 |
| Ingebjørg Larsen AS | Health & social care | 2026 |
| Ingeborg Aas Vei 1 AS | Real estate | 2017 |
| Ingeborg Bjørnevik Holding AS | Financial services | 2008 |
| Ingeniør Mo-Bjørkelund AS | | 2019 |
| Ingeniørfirma Paul Jørgensen AS | Manufacturing | 1994 |
| Ingenuity AS | Administrative & support | 2021 |
| Ingotech AS | Professional & scientific | 2004 |
| Ingrasso AS | Real estate | 1999 |
| Ingro AS | Professional & scientific | 2005 |
| Ingun Moe Invest AS | Financial services | 2005 |
| Ingurei AS | Financial services | 2011 |