The son of Sigmundr and Borghildr, born at Brálund. On the night of his birth the Norns came to determine his fate, and they decreed him a most famous prince. His parents named him Helgi, after Helgi Hjörvarðsson. He was fostered by a certain Hagal, who is not mentioned elsewhere.
When he was fifteen years old, Helgi secretly explored the court of King Hunding, an enemy of the Volsungs, under the name of Hamal. When he thought himself safe he sent word of his true identify, and Hunding ordered his men to capture him. Helgi narrowly escaped by putting on the clothes of a bond-woman and working in a mill. He later slew Hunding and so received the name Helgi Hundingsbane.
Hunding's sons — Álfr, Eyiólf, Hiörvard and Hávard — demanded from Sigmundr financial compensation, but Helgi refused to pay the blood-fine. The brothers then declared war but were slain in the ensuing battle.
As Helgi sat under the Arastein, a band of valkyries appeared to choose who of the fallen would take their place in Valhalla. One of the valkyries, Sigrún, Högni's daughter, informed Helgi that her father had betrothed her to Höðbroddr, the fierce son of Granmarr, king of the Hniflungs, but that she had chosen him instead. She invoked his aid to save her from Höðbroddr, and Helgi assembled a great army and sailed to Frekastein. During their voyage they experienced a perilous storm but the intervention of Sigrún saved them from the hand of Rán.
The ships arrived at Unavagár, where they were challenged by Guðmundr, another of Granmarr's sons, and he and Helgi's half-brother Sinfjötli engaged in a flyting contest. Guðmundr returned home with intelligence of the hostile arrangement, whereupon the sons of Granmarr collected a host, which included Högni, the father of Sigrún, and his sons Bragi and Dagr. Helgi and his men were victorious in the great battle and all the sons of Högni and their chiefs were slain, with the exception of Dagr. Helgi and Sigrún wed and had many sons. Dagr, who was bound by honor to avenge his father and brother, invoked Odin's help. Odin gave him his spear and with this spear Dagr killed Helgi.
A mound was raised for Helgi; and when he came to Valhalla, Odin offered him rule over all jointly with himself. A serving woman passing at evening by Helgi's mound, saw him riding towards it with many men. She told Sigrún, who then entered the mound. The two met for a final time and at dawn Helgi said to his beloved that he must return to Valhalla over Vindhiálm's bridge. Sigrún's life was shortened by grief and mourning.
- Helgakviða Hundingsbana I & II.