Ooijer made his senior international debut for Holland on the 5th June 1999 in a difficult match against Brazil, in which he came on as a substitute for Reiziger, in a game which ended in a 2-2 draw. He has been used regularly for Holland, when he stays free from injuries, which he is rather prone to. Until today, he has earned 40 caps for Holland. He was called by van Basten for Euro 2008 and assigned the number 2 shirt.