[1] He was present at the Battle of Stamford Bridge in England in 1066 where his father, King Harald Hardrada, saw defeat and was killed in action, an event that directly preceded his kingship.

During his rule, Olaf made peace with regards to earlier royal conflicts with the church, strengthened the power of the monarchy, and is traditionally credited with founding the city of Bergen circa 1070.

The latter resulted in, among other things, the reorganization of the body-guard and of measures under which key cities, especially Bergen, could better serve as a royal residence.

[6][7] The death of Harald Hardrada and the serious defeat suffered by the Norwegians in 1066 tempted the Danish king, Svend Estridsen, to prepare for an attack on Norway.

Harald Hardrada had developed a continuing conflict with the Archbishopric of Bremen due to the archbishop's authority over the Norwegian church.

There are strong indications that the government of King Olaf began writing secure provincial laws to a greater extent.

[9] King Olaf died of illness on 22 September 1093 in Haukbø, Rånrike, then part of Norway (now Håkeby, Tanum Municipality, Sweden).

The circumstances of its arrival from Norway to a Native American village in the present US territory remain unclear and highly disputed.