| Gry T. H. Raum AS | Wholesale & retail | 2022 |
| Grønlia AS | Real estate | 2018 |
| Grønnbakken Masseuttak AS | Mining & quarrying | 2023 |
| Grønnebakkan Andelsbarnehage SA | Education | 1994 |
| Grønnebakkan Panorama AS | Real estate | 2019 |
| GST AS | Administrative & support | 2025 |
| GT Sea AS | Real estate | 2022 |
| Gullbas Holding AS | | 2022 |
| Gullhesten AS | Wholesale & retail | 2020 |
| Gummes Trafikkskole AS | Education | 2010 |
| Gynharstad AS | Health & social care | 2014 |
| Gårdeierforeningen Harstad AS | Real estate | 2019 |
| Gårdselskapet Øysteins GT 4 AS | Real estate | 1985 |
| H/T Eiendom AS | Real estate | 2022 |
| H5 Eiendomsutvikling AS | Real estate | 2009 |
| Habit Software AS | Information & communication | 1993 |
| Hagebakken Invest AS | | 2026 |
| Hall-Hofsø Kommunikasjon Limited Nuf | Arts & recreation | 2007 |
| Hallaise Management AS | Information & communication | 2019 |
| Halvdans Gate 5 AS | Real estate | 2014 |
| Hammer Music AS | Arts & recreation | 2023 |
| Hamneshaugen AS | Real estate | 2000 |
| Haneseth Harstad AS | Construction | 1991 |
| Hangryaf AS | Information & communication | 2023 |
| Hanssen Eiendom AS | Real estate | 1999 |
| Haralds Musikk AS | Arts & recreation | 2024 |
| Harder AS | Professional & scientific | 2010 |
| Harder Eiendom AS | Real estate | 1980 |
| Hardfør Utvikling AS | Professional & scientific | 2025 |
| HARJO1 Holding AS | | 2021 |
| Harstad 360 AS | Real estate | 1987 |
| Harstad Aggregatservice AS | Wholesale & retail | 2007 |
| Harstad Aggregatservice Eiendom AS | Real estate | 2000 |
| Harstad Arena AS | Arts & recreation | 2025 |
| Harstad Batteriservice AS | Wholesale & retail | 1993 |
| Harstad Bensin Og Service AS | Wholesale & retail | 2000 |
| Harstad Bil AS | Other services | 1986 |
| Harstad Bil Eiendom AS | Real estate | 2013 |
| Harstad Bil Holding AS | Wholesale & retail | 2012 |
| Harstad Bil Og Eiendom AS | Real estate | 2025 |
| Harstad Bilskade AS | Other services | 2022 |
| Harstad Bilskade Holding AS | Other services | 2021 |
| Harstad Bolig Eiendommer AS | Real estate | 2018 |
| Harstad Dekksenter AS | Other services | 2013 |
| Harstad Denvest AS | Financial services | 2018 |
| Harstad Drift & Servicepartner AS | Construction | 2013 |
| Harstad Eiendomsmegling AS | Real estate | 2023 |
| Harstad Eiendomsutvikling AS | Real estate | 2019 |
| Harstad Elektro AS | Construction | 1988 |
| Harstad Elektro Holding AS | Construction | 2002 |
| Harstad Elgvald Sør SA | Real estate | 2026 |
| Harstad Emarked AS | Wholesale & retail | 2020 |
| Harstad Finans AS | Professional & scientific | 1996 |
| Harstad Gamle Posthus AS | Real estate | 2003 |
| Harstad Haandtverksbryggeri AS | Manufacturing | 2014 |
| Harstad Havbadstue AS | Administrative & support | 2021 |
| Harstad Helsekost AS | Wholesale & retail | 2022 |
| Harstad Idrettlslag Eiendom AS | Arts & recreation | 2004 |
| Harstad Innrammingsforretning AS | Manufacturing | 1997 |
| Harstad Jakt Og Fritids Bekledning Da | Wholesale & retail | 1999 |
| Harstad Kontoreiendom AS | Real estate | 2022 |
| Harstad Kulturhus AS | Arts & recreation | 1992 |
| Harstad Lekeland AS | Arts & recreation | 2025 |
| Harstad Logopedtjeneste AS | Health & social care | 2023 |
| Harstad Låsservice AS | Wholesale & retail | 2017 |
| Harstad Marina AS | Wholesale & retail | 2011 |
| Harstad Maritime Senter AS | Real estate | 2020 |
| Harstad Maskin AS | Construction | 2014 |
| Harstad Maskin Eiendom AS | Construction | 2015 |
| Harstad Maskin Holding AS | Construction | 2014 |
| Harstad Maskinutleie AS | Administrative & support | 2026 |
| Harstad Mek Verksted AS | Manufacturing | 1995 |
| Harstad Montessoriskole SA | Education | 2013 |
| Harstad New Energy AS | Professional & scientific | 2000 |
| Harstad Nær AS | Wholesale & retail | 2014 |
| Harstad Omsorgstjenester AS | Health & social care | 2021 |
| Harstad Optikk AS | Wholesale & retail | 2008 |
| Harstad Osteopati AS | Health & social care | 2012 |
| Harstad Parkering AS | Transport & logistics | 2021 |
| Harstad Psykologi AS | Health & social care | 2026 |
| Harstad Publishing AS | Information & communication | 2020 |
| Harstad Restaurantdrift AS | Hospitality | 1999 |
| Harstad Retail AS | Wholesale & retail | 2020 |
| Harstad Rør AS | Construction | 1995 |
| Harstad Sentrum AS | Professional & scientific | 2019 |
| Harstad Skipsindustri AS | Manufacturing | 1988 |
| Harstad Spyleservice AS | Water & waste | 2018 |
| Harstad Spyleservice Eiendom AS | Real estate | 2018 |
| Harstad Spyleservice Holding AS | Water & waste | 2017 |
| Harstad Studentband Da | Arts & recreation | 2019 |
| Harstad Stålmontasje Drift AS | Construction | 2010 |
| Harstad Stålmontasje Eiendom AS | Real estate | 1997 |
| Harstad Takst AS | Professional & scientific | 2012 |
| Harstad Tannhelsesenter AS | Health & social care | 2007 |
| Harstad Tannhelsesenter Eva-Britta Thode Hansen AS | Health & social care | 2007 |
| Harstad Tannhelsesenter May-Elin Balk Thomassen AS | Health & social care | 2007 |
| Harstad Taxi AS | Transport & logistics | 1995 |
| Harstad Tidende AS | Information & communication | 2004 |
| Harstad Trading AS | Wholesale & retail | 1983 |
| Harstad Trading Holding AS | Wholesale & retail | 2020 |