Haakon was the son of Sigurd Haakonsson, Jarl of Lade and ruler of Trøndelag and Hålogaland. His mother was Bergljot Toresdatter, daughter of Tore Ragnvaldsson, Earl of Møre. Adam of Bremen wrote that he was "of the stock of Ivar (possibly Ivar the Boneless) and descended from a race of giants". In the sagas, Haakon claimed descent from the divine linage of Sæming, son of Odin. The Hakon Jarl Runestones in Sweden may refer to him.
Haakon became earl after his father was killed by King Harald Greyhide's men in 961. He warred with King Harald for some time, until he was forced to flee to Denmark and Harald Bluetooth. In Denmark he conspired with Harald Bluetooth against Harald Greyhide.
Jarl Haakon arranged the death of Harald Greyhide around 971 with the connivance of Harald Bluetooth, who had invited his foster-son to Denmark to be invested with new Danish fiefs. Civil war broke out between Jarl Haakon and the surviving brothers of Harald Greyhide, but Haakon proved victorious. After this, Haakon Jarl ruled Norway as a vassal of Harald Bluetooth, but he was in reality an independent ruler. For Harald, he attacked Götaland and killed its ruler Jarl Ottar. When Haakon was in Denmark, Harald Bluetooth forced him to accept baptism and assigned him clergymen to take to Norway to spread Christianity. When a favourable wind came for Haakon to leave, he commanded the clergymen to return ashore.
Around 973-974, he went to Denmark to help Harald Bluetooth of Denmark in his defense against the Holy Roman Emperor Otto II. Otto's forces successfully opposed an attempt by Harald to throw off the German yoke. After that Haakon paid no taxes to Denmark.
Haakon was a strong believer in the old Norse gods, and when Harald Bluetooth attempted to force Christianity upon him around 975, Haakon broke his allegiance to Denmark. In 977 Vladimir I of Kiev fled to him, collecting as many of the Viking warriors as he could to assist him to recover Novgorod, and on his return the next year marched against Yaropolk I of Kiev. In 986, a Danish invasion fleet led by the fabled Jomsvikings was defeated at the Battle of Hjörungavágr.
In 995, a quarrel broke out between Haakon and the Trønders just as Olaf Tryggvason, a descendant of Harald Fairhair arrived. Haakon quickly lost all support, and was killed by his own slave and friend, Tormod Kark, while hiding in the pig sty in the farm Rimul in Melhus. Jarlshola is the location in Melhus thought to have been the hiding place of Haakon Jarl and Tormod Kark on their last night before the infamous murder at Rimul. After his death, Haakon Jarl's two sons Eirik Håkonson and Sveinn Hákonarson, fled for protection to the king of Sweden, Olof Skötkonung.
- Eirik Håkonson (960s – 1020s), would avenge his father at the Battle of Svolder and then govern Norway with his half-brother, Sveinn Hákonarson
- Sveinn Hákonarson (died c. 1016), co-ruler of Norway
- Aud Haakonsdottir, married the Swedish king Eric the Victorious, according to Yngvars saga víðförla
- Bergljót Haakonsdottir, married Einar Tambarskjelvar
- Sigrid Haakonsdottir, mother of Ivar Hvide, Jarl of Oppland
According to Skáldatal, Haakon had the following court poets:
- Eyvindr Finnsson
- Einarr skálaglamm
- Tindr Hallkelsson
- Skafti Þóroddsson
- Þórólfr munnr
- Eilífr Guðrúnarson
- Vigfúss Víga-Glúmsson
- Þorleifr jarlsskáld
Jarl Haakon is a central figure in Håkon og Kark which is performed annually at the Korsvikaspillet festival in Korsvika in Trondheim. The play is based on the story of Jarl Haakon and Tormod Kark as portrayed in the Sagas by Snorri Sturluson. The first play was a poetic tableau that was made in connection with the 800-year anniversary of the Lade Church (Lade kirke) in 1989 and repeated two years later. In 1995, Idar Lind wrote a new script. The music is composed by Frode Fjellheim.
Haakon SigurdssonDied: 995