| Alta Fargehandel AS | Construction | 1991 |
| Alta Fiskeriselskap AS | Agriculture & fishing | 2020 |
| Alta Fiskeriservice AS | Real estate | 1994 |
| Alta Fjernvarme AS | Energy | 2016 |
| Alta Fotklinikk AS | Other services | 2022 |
| Alta Frakt AS | Transport & logistics | 2024 |
| Alta Giftshop AS | Wholesale & retail | 2020 |
| Alta Golfpark AS | Arts & recreation | 2008 |
| Alta Graving Og Transport AS | Construction | 2004 |
| Alta Guiding AS | Administrative & support | 2023 |
| Alta Gynekologi AS | Health & social care | 2013 |
| Alta Holding AS | | 2025 |
| Alta Hybelbygg AS | Real estate | 2006 |
| Alta Hårpleie AS | Other services | 2014 |
| Alta Industribygg AS | Real estate | 1968 |
| Alta Kjøkken Og Interiør AS | Wholesale & retail | 2010 |
| Alta Kraftlag SA | Energy | 1948 |
| Alta Kran Og Transport AS | Transport & logistics | 2012 |
| Alta Kristne Grunnskole SA | Education | 2003 |
| Alta Kube AS | Wholesale & retail | 2024 |
| Alta Kvinnehelse AS | Health & social care | 2024 |
| Alta Lakk AS | Other services | 2006 |
| Alta Lastebilsentral AS | Transport & logistics | 2006 |
| Alta Lastebilsentral Eiendom AS | Real estate | 1970 |
| Alta Live Scene AS | Arts & recreation | 2025 |
| Alta Logistics AS | Transport & logistics | 2009 |
| Alta Lydstudio AS | Arts & recreation | 2000 |
| Alta Magedans Og Yoga AS | Education | 2015 |
| Alta Maritim AS | Agriculture & fishing | 2023 |
| Alta Maskinering AS | Manufacturing | 2020 |
| Alta Matteutleie AS | Administrative & support | 2009 |
| Alta Mc-Shop AS | Wholesale & retail | 2013 |
| Alta Mekaniske Verksted AS | Manufacturing | 2007 |
| Alta Motorsenter AS | Wholesale & retail | 1993 |
| Alta Offentlig Eiendom AS | Real estate | 2023 |
| Alta Optikk AS | Wholesale & retail | 2021 |
| Alta Psykomotorisk Fysioterapi AS | Health & social care | 2017 |
| Alta Racing Service AS | Wholesale & retail | 2015 |
| Alta River Camping AS | Hospitality | 2012 |
| Alta Saubeitelag Ba | Agriculture & fishing | 1952 |
| Alta Sauetransport SA | Transport & logistics | 1995 |
| Alta Skiferbrudd Eiendom AS | Real estate | 2015 |
| Alta Skiferbrudd SA | Mining & quarrying | 1933 |
| Alta Skiferprodukter AS | Mining & quarrying | 2002 |
| Alta Sol Holding AS | Wholesale & retail | 2022 |
| Alta Strand Camping & Apartment AS | Hospitality | 2005 |
| Alta Stål & CNC Maskinering AS | Manufacturing | 2009 |
| Alta Stål Holding AS | | 2020 |
| Alta Takstoler AS | Manufacturing | 2008 |
| Alta Taxi AS | Transport & logistics | 2001 |
| Alta Trafikkskole AS | Education | 2012 |
| Alta Transport AS | Transport & logistics | 2012 |
| Alta Trefelling AS | Agriculture & fishing | 2018 |
| Alta Utleie Og Eiendom AS | Real estate | 2021 |
| Alta Utvikling AS | Real estate | 2023 |
| Alta Veiservice AS | Transport & logistics | 2026 |
| Alta Vest AS | Real estate | 2011 |
| Alta Værring Ba | Agriculture & fishing | 1983 |
| Alta Zoo AS | Wholesale & retail | 1997 |
| Altabunad AS | Manufacturing | 2007 |
| Altaelva Eiendom AS | Real estate | 2019 |
| Altafjord Gjestegaard Og Spa AS | Hospitality | 2009 |
| Altafjord Panorama AS | Real estate | 2007 |
| Altagård Utleie AS | Professional & scientific | 2011 |
| Altahøyden Eiendom AS | Real estate | 2020 |
| Altahøyden Utbygging AS | Real estate | 2012 |
| Altaie Frisør AS | Other services | 2017 |
| Altaparken AS | Real estate | 2023 |
| Altapizza AS | Hospitality | 2016 |
| Altaturer AS | Administrative & support | 2012 |
| Altaveien 73 AS | Real estate | 2007 |
| Altaveien 77 AS | Real estate | 2026 |
| Altaveien 83 AS | Real estate | 2017 |
| Altaveien 99 AS | Real estate | 2020 |
| Altenfjord Transport AS | Transport & logistics | 2013 |
| Altera Invest AS | | 2025 |
| Althus AS | Construction | 2017 |
| Alut AS | Energy | 2020 |
| Am-Development AS | Information & communication | 2024 |
| Amigo Studio Da | Information & communication | 2000 |
| Ams Eiendom AS | Real estate | 2022 |
| Amundsen.Ø Holding AS | | 2023 |
| Anders Løvland Invest AS | | 2021 |
| Andersen Arbeidsdykking AS | Construction | 2018 |
| Andersen Skog Og Utemiljø AS | Agriculture & fishing | 2021 |
| Andersens Utleiebygg AS | Real estate | 2019 |
| Andreassen Maskin & Transport AS | Mining & quarrying | 2016 |
| Anita Bjørnæs Eiendom AS | Real estate | 1997 |
| Anja Graven Invest AS | Professional & scientific | 2022 |
| Anlegg Nord AS | Construction | 2013 |
| Anleggsgartner Stian Olsen AS | Administrative & support | 2022 |
| Anleggsteknikk Alta AS | Construction | 2010 |
| Anne Marit Østmo AS | Health & social care | 2017 |
| Annsby Helse AS | Health & social care | 2021 |
| Ans Sentrumsbygget | | 1985 |
| Antaeus AS | | 2009 |
| Antalia Kebab Ans | Hospitality | 2001 |
| Aogb Holding AS | | 2025 |
| Aparts AS | Construction | 2014 |
| Apex Trading AS | Financial services | 2005 |