He is the protagonist of Hallfreðar saga according to which he was the court poet first of Hákon Sigurðarson, then of Óláfr Tryggvason and finally of Eiríkr Hákonarson.
A significant amount of poetry by Hallfreðr has been preserved, primarily in Hallfreðar saga and the kings' sagas but a few fragments are also quoted in Skáldskaparmál.
In his lausavísur Hallfreðr was an unusually personal skald, offering insight into his emotional life and, especially, his troubled and reluctant conversion from paganism to Christianity under the tutelage of king Óláfr.
Ǫll hefr ætt til hylli Óðins skipat ljóðum (algildar man'k) aldar (iðjur várra niðja); en trauðr, því't vel Viðris vald hugnaðisk skaldi, legg'k á frumver Friggjar fjón því't Kristi þjónum.
The whole race of men to win Óðinn's grace has wrought poems (I recall the exquisite works of my forebears); but with sorrow, for well did Viðrir's [Óðinn's] power please the poet, do I conceive hate for the first husband of Frigg [Óðinn], now I serve Christ.