Haakon was the younger surviving son of Magnus the Lawmender, King of Norway, and his wife Ingeborg of Denmark.

[4] Haakon succeeded to the royal throne when his older brother died without sons.

[6] In 1295, Haakon married firstly with Isabelle, daughter of Jean I, Count of Joigny, but she died in 1297 without children.

[7] During Haakon's reign, Oslo gradually took over the functions of capital of Norway from Bergen, though there was no official pronouncement of this at any time.

Remains of two people, deemed to be Haakon and Eufemia, were discovered during excavations of the ruins of that church and reinterred in the royal mausoleum at Akershus Castle.