He was the eldest son of King Liloa, 12th Alii Aimoku of Hawaii. He succeeded on the death of his father in the year 1495.
His brother Umi was the son of Liloa and a commoner. Umi came to the capital at Waipio and the king then ordered his idols, that the ceremony of oki-piko might be performed on Umi, and it was done. When Hakau heard the sound of the drum, he asked what it meant; and the people answered, 'It is the drum at the oki-piko of Liloa's new-found son, Umi.' On hearing that Liloa had a new son, Hakau was full of wrath, and he came to Liloa with the question, 'Is this your son?' To this Liloa ayed assent and at the same time tried to placate Hakau, saying, 'You will be king, and he will be your man. You will have authority over him.' With words like these Liloa tried to soften Hakau's anger towards Umi. Hakau was outwardly appeased, but there was a hypocritical reservation within.
Shortly after his father, Līloa’s, death, a royal mausoleum was built by Hākau as a final resting place for the bones of Līloa. The mausoleum known as Hale o Līloa (House of Līloa) was built within the Paka‘alana heiau. The bones of Līloa were bundled up in a kā‘ai (wicker container) and placed in the hale to be revered as ancestral remains. After the death of Liloa, Umi submitted himself dutifully to Hakau. Hakau, however, hated Umi cordially and treated him with great contempt and spitefulness. He missed no opportunities to thwart his brother Umi, and openly reviled him for his low birth, insisting that his mother was a woman of low degree. Once, when Umi rode upon Hakau's surfboard, Hakau said to him, 'Don't you use my surfboard. Your mother was a common, plebeian woman of Hamakua. My board is kapu. I am an alii.' When Umi chanced, on one occasion, to put on a malo (loincloth) belonging to Hakau, Hakau insulted and upbraided him, saying, 'Don't you wear my malo. I am an alii. Your mother was a low-class woman of Hamakua.' Thus it was that Hakau insulted and actually offered violence to Umi so that finally he made up his mind to leave the court of Hakau secretly.
He was desposed by his lower-ranking brother 'Umi-a-Liloa in 1510 because of his mistreatment of other Ali‘i, kahuna (priests), and maka‘āinana alike made his name synonymous with evil. For example, he would torture and kill anyone he felt was more physically attractive than he. Sources say that he either was stoned to death by the commoners or slain by his brother Umi. One of ‘Umi’s first acts as king was to offer up the body of Hākau and his supporters at the heiau as sacrifice to the war god Kū. According to the mo‘olelo, Kū’s tongue came down and consumed the sacrifices amidst thunder and lightning.
Hakau's wife was Kukukalani-o-pae and his daughter's name was Pinea. The life of his family was spared during the conflict; in fact, in after life Hakau's granddaughter Haukanuinonakapuakea became one of the wives of Umi's son Keawenui-a-Umi.