Grifo was the illegitimate son of Charles Martel, an important leader of the Franks.

After the death of Charles Martel power may well have been intended for his illegitimate son, Grifo, as well as Pippin (the Short) and Carloman, Martel's legitimate children. He was lured into a trap by his half-brothers, however, and imprisoned in a monastery.

On his escape in 747, Duke Odilo of Bavaria gave his support to Grifo. Duke Odilo died a year later, providing opportunity for a decisive intervention by Pippin the Short. Odilo's infant son, Tassilo, was imposed as a subordinate duke.

Grifo and his supporters continued to resist until he was killed in 753.