Unlike some other saints he was born into a very wealthy, noble family.
Toul at this time, although a part of the Holy Roman Empire, enjoyed a great deal of independence under its prince-bishops. Gerard proved a successful and respected ruler, governing the principality for thirty-one years.
He established many religious schools in the see, inviting scholars from across Europe, namely Greeks, to study and teach at Toul. He also rebuilt many churches, notably Toul Cathedral. According to the Vita Sancti Gerardi, Gerard had the relics of both Saint Mansuetus and Saint Aprus, earlier bishops of Toul, brought into the city and placed in the church of St. John the Baptist while he was ill.
It is believed he entered activity in the Church due to his mother dying by lightning strike, an event he believed to be divine judgment for his sins.
He died on April 23rd, 994 AD.
He was canonized in 1050 by Pope Leo IX (Bruno of Eguisheim), who had succeeded him as bishop of the see.
His feast day is celebrated on 23 April.