Chagnoald (Cagnoald, Cagnou) (died 633 AD) was a Frankish bishop of Laon during the 7th century. The family to which Chagnoald belonged is known as the Faronids, named after his brother Saint Faro, who was bishop of Meaux, while his sister was Saint Burgundofara, who founded the convent of Faremoûtiers. They were the children of the chancellor to Dagobert I, Chagneric.
Chagnoald became a monk at Luxeuil, and was later ordained bishop of Laon. In that position, he once angered the king, Theuderic II, by criticizing him for his immoral conduct. Theodoric in response exiled Chagnoaldus from his territories in 610. Chagnoald left his see, finding refuge in the territory of Theuderic II, and working with Columbanus as a missionary in the area of Lake Constance.
Theodoric later gained control of this territory as well. Columbanus was banished, and left for Rome, with Chagnoald accompanying him. On the death of Columbanus, Chagnoald returned to his old diocese, and resumed his duties as bishop. He participated in the Council of Reims in 630.