He was the grandson of King Harald Hardrada, son of King Magnus and nephew of King Olaf Kyrre. Haakon was born around the same time his father died. He was raised as a foster son by Tore på Steig of Gudbrandsdalen on the farm Steig in Fron. In 1090, he undertook a Viking expedition to Bjarmaland, today the area of Arkhangelsk in northern Russia.^[2]

After the death of Olav Kyrre he was hailed as King of Norway in Trondheim, while his cousin, King Magnus Barefoot, was hailed in Viken. He soon came into conflict with King Magnus and war seemed inevitable. In 1095, Magnus Berrføtt prepared an armed action against Haakon, but was surprised by the strong position held by his cousin. When Haakon learned that Magnus had come to Trondheim, he went across the Dovrefjell mountain range. However, Haakon suddenly died during the trip over Dovrefjell. Magnus subsequently ruled as sole king of Norway. He captured Tore på Steig who was subsequently hanged.^[3] He was buriedbin Christ Church in Trondhjem.

By his wife Johanna he was the father of Harald Håkonsson (Trondheim, ca. 1091 - Trondheim, ca. 1167), father of Erik Haraldsson Sure (Trondheim, 1120 - Trondheim, 1198), married to Ragnhild Hansdatter (ca. 1123 - ca. 1194), parents of Håkon Eriksson Sure (Trondheim, 1145 - Trondheim, 1217), father of Harald Håkonson Sure (1172 - 1213), father of Auden Haraldsen Sure (Trondheim, ca. 1200 - Trondheim, 1276), father of Pål Audenson Sure (Trondheim, 1235 - Trondheim, 1289), who had three daughters married with issue, and Ingeborg Audunsdatter Sure (Trondheim, 1238 - Tingvoll, 1296), married to Ivar Toraldeson Aspen (Kvinnherad, 1237 - Kvinnherad, 1304), and had issue.