Silooy was born in Rotterdam. He played as a right or central defender and is one of the legends of Ajax Amsterdam, where he made his debut on 3 May 1981, playing over 250 league games for the Amsterdam club in two separate periods. Silooy also played for Matra Racing, Arminia Bielefeld, De Graafschap and the amateurs of GVV Unitas from Gorinchem. He played in the 1996 UEFA Champions League Final against Juventus, but missed a key penalty in the shootout which Ajax ultimately lost.