He was the son of Emmanuel de Sayeleer and the nephew of Aegidius I, Jan I en Raphael Sadeler.

His early engravings were mostly faithful copies of works by Albrecht Dürer in the Imperial collection and copies of paintings by notable Italian painters such as Raphael, Tintoretto, Parmigianino, Barocci and Titian or by Northern painters who worked there, such as Paul Bril and Denys Calvaert.

In Prague he also engraved portraits of the notables of Rudolf's court, and collaborated with Spranger, Joseph Heintz the Elder, Jacobus Typotius and his friend Anselmus Boece de Boodt (1550–1632), Rudolf II's gemologist and physician.

[4][5] According to Michael Bryan, "He used the graver with a commanding facility, sometimes finishing his plates with surprising neatness, when the subject required it; at other times his burin is broad and bold.

He had many pupils, including Wenzel Hollar and Joachim von Sandrart, who wrote his biography.