Gui Guerrejat ("the warrior") was the fifth son of William VI of Montpellier.
When still a boy, in 1146, he inherited the castles of Paulhan and le Pouget from his father.
In this capacity Gui and John attended the conference at Mezouls in 1174 at which Raymond V of Toulouse and Alfonso II of Aragon negotiated an agreement with the young William VIII.
In 1177 he joined Bernard Ato V of Nîmes and Agde, Countess Ermengarde of Narbonne, and his nephews William VIII and Gui Burgundion, in an alliance in opposition to Raymond V of Toulouse, who now ruled Melgueil as the widower of Ermessende of Pelet.
According to her Occitan vida (in the Biographies des Troubadours), the trobairitz Azalais de Porcairagues was the lover of Gui Guerrejat; her one surviving poem seems to be addressed to him.