He was born circa 1520 in Turnhout (so his surname may not be inherited), the first of a series of cities where he worked in the Habsburg duchy of Brabant (all in the central part, presently the Flemish (Belgian) province of Antwerp). Gerard worked in and around Antwerp, a wealthy port city, from 1545 as singer and choirmaster (working at the cathedral before 1559), becoming in 1559 maître de chapelle at Saint-Gommarus of Lier(re). He entered holy orders, but no date for his ordination is established. In 1562, he became music director of the (Marian) Confrérie de Notre-Dame at Antwerp Cathedral, and was maître de chant there in 1563–71; after the “Beeldenstorm” (a violent phase of the rebellion against the Spanish persecution of protestantism which systematically smashed Catholic ecclesiastic art) destroyed in 1566 both the church organ and the substantive collection of music, his main activity for years was to copy masses and motets for liturgical use. On May 2, 1571, recruited trough the duke of Alva, king Philip II’s trusted general and — hated — de facto governor in the rebellious Low Countries, he succeeded the little-known Jean de Bonmarché as maestro di capilla (the fourth of 7 successive “Flemish” incumbents in 77 years) to the capilla flamenca (“Flemish chapel”) at the royal Habsburg court in Spain; after his death he would be succeeded by Georges de la Hèle (qv).

Another musician, Jan-Jacob van Turnhout (or in French Jean-Jacques de Turnhout, born ca. 1545 and died after 1618, who was maître de chapelle at Brussels from 1594 to 1618, may have been related to Gérard (possibly Gerard’s much younger brother or son).