Jozef-Ernest van Roey was born in Vorselaar, as the first of the five children of Stanislas and Anna-Maria (née Bartholomeus) van Roey. His siblings were named Bernadette, Louis, Véronique, and Stephanie (who became a nun). He was baptized the same day of his birth in the parish church of Vorselaar. Van Roey studied under the Jesuits in Vorselaar before entering Saint-Joseph School in Herentals in 1885. He graduated in 1892, whence he entered the minor seminary in Mechelen. From 1894 to 1897, he studied theology at the Major Seminary of Mechelen. He was ordained to the priesthood by Cardinal Pierre-Lambert Goossens on 18 September 1897.