| Hydor Holding AS | Information & communication | 2022 |
| Hydor Manco AS | | 2022 |
| Hydor Midco AS | | 2022 |
| Hydra Capital AS | | 2020 |
| Hydra Defence AS | Professional & scientific | 2017 |
| Hydrakraft AS | Energy | 2022 |
| Hydrawell Holding AS | Professional & scientific | 2016 |
| Hydreaft AS | | 2019 |
| Hydria Water AS | Professional & scientific | 2024 |
| Hydro Agri Europe SA | Wholesale & retail | 1997 |
| Hydro Aluminium AS | Manufacturing | 1947 |
| Hydro Aluminium Deutschland GmbH | Wholesale & retail | 1999 |
| Hydro Building Systems Southwest SL | Professional & scientific | 2014 |
| Hydro Chemicals AB | Wholesale & retail | 1998 |
| Hydro Energi AS | Energy | 1903 |
| Hydro Energi Invest AS | Water & waste | 2018 |
| Hydro Extruded Solutions AS | Manufacturing | 2012 |
| Hydro Extrusion USA, LLC | Manufacturing | 2016 |
| Hydro Havrand AS | Manufacturing | 2021 |
| Hydro Kapitalforvaltning AS | Financial services | 2006 |
| Hydro Max Kolobius | Construction | 2014 |
| Hydro Rein AS | Professional & scientific | 2023 |
| Hydro Rein Energy Solutions AS | Energy | 2021 |
| Hydro Rein Invest AS | Professional & scientific | 2020 |
| Hydro Renewables Holding AS | Energy | 1900 |
| Hydro Renewables Norway Holding AS | Energy | 2022 |
| Hydroasset 1 AS | Energy | 2024 |
| Hydroasset AS | Energy | 2023 |
| Hydrogen Storage AS | Professional & scientific | 2020 |
| Hydronor AS | Energy | 2015 |
| Hydroplant Technologies AS | Professional & scientific | 2024 |
| Hydrotek AS | Construction | 2023 |
| Hydroterm AS | Construction | 2025 |
| Hydroveks AS | Professional & scientific | 2021 |
| Hydroza AS | Professional & scientific | 1998 |
| Hyene AS | | 2024 |
| Hygg AS | Wholesale & retail | 2018 |
| Hygge Living AS | Wholesale & retail | 2015 |
| Hyggebasert Føretak AS | Other services | 2021 |
| Hyggebasert Hellas AS | Real estate | 2025 |
| Hyggeform AS | Professional & scientific | 2020 |
| Hyggelig AS | | 2026 |
| Hyggelig Eiendom AS | Real estate | 2021 |
| Hyggelig Utvikling AS | Real estate | 2006 |
| Hyggeligbakken AS | Real estate | 2016 |
| Hyggeveien 16 AS | Real estate | 2016 |
| Hyggi AS | Professional & scientific | 2022 |
| Hygglo AS | Information & communication | 2015 |
| Hygotech AS | Professional & scientific | 2017 |
| Hylander V&S AS | Construction | 2019 |
| Hylas Holding AS | | 2021 |
| Hylkje Eiendom AS | Real estate | 2020 |
| Hylkjeflaten 10 AS | Real estate | 2006 |
| Hyllbekk Consulting Group AS | Professional & scientific | 2023 |
| Hylle Kvartal B58 AS | Real estate | 2025 |
| Hylle Kvartal B62 AS | | 2026 |
| Hylle Sota 11 AS | Real estate | 2025 |
| Hyllez Holding AS | | 2022 |
| Hyllo AS | Information & communication | 2026 |
| Hylster Clothing Company AS | Wholesale & retail | 2019 |
| Hymen Projects Da | Information & communication | 2014 |
| Hymn Ans | Arts & recreation | 2013 |
| Hyosung Heavy Industries Corporation | Professional & scientific | 2021 |
| Hypefactors Norge AS | Professional & scientific | 2025 |
| Hyper Games AS | Information & communication | 2012 |
| Hypercube Holding AS | | 2020 |
| Hyperkon AS | Information & communication | 2016 |
| Hyperlink Consulting Group Ans | Information & communication | 2000 |
| Hypermat AS | Real estate | 2009 |
| Hypersoft Ans | Information & communication | 1992 |
| Hyperspace AS | Information & communication | 2024 |
| Hypertro AS | Information & communication | 2025 |
| Hypetrain Invest AS | | 2025 |
| Hypha Energy Nordics SA | Energy | 2026 |
| Hypogeum AS | Hospitality | 2019 |
| Hypopressiv Trening Norge AS | Education | 2020 |
| Hyre AS | Administrative & support | 2017 |
| Hyre Mipco AS | Wholesale & retail | 2022 |
| Hysj Arkitektur AS | Professional & scientific | 2009 |
| Hystadveien Utvikling AS | Real estate | 2021 |
| Hyster-Yale UK Limited | Wholesale & retail | 2010 |
| Hystorsys AS | Professional & scientific | 2005 |
| Hysværet AS | Real estate | 2022 |
| Hytte Daniels Ans | Hospitality | 2025 |
| Hytte Michels-Winkelhuijzen Ans | Hospitality | 2025 |
| Hytte Schoon Ans | Hospitality | 2025 |
| Hyttebutikken Stabekk AS | Wholesale & retail | 2013 |
| Hytteforvaltning AS | Real estate | 2012 |
| Hyttely AS | Real estate | 2026 |
| Hyttemester AS | Construction | 2023 |
| Hytten Invest AS | Financial services | 2014 |
| Hyttero AS | Information & communication | 2005 |
| Hyttetjenester AS | Information & communication | 2015 |
| Hyttevin AS | Wholesale & retail | 2019 |
| Hyundai Motor Norway Nuf | Wholesale & retail | 2014 |
| Hyyr AS | Information & communication | 2023 |
| Hyzer Sport AS | Wholesale & retail | 2020 |
| HZ Consulting AS | Professional & scientific | 2022 |
| HZ Holding AS | Professional & scientific | 2020 |
| HZR AS | Financial services | 2017 |