His former clubs as a player include RVV HOV, Feyenoord Rotterdam, Holland Sport, R.W.D. Molenbeek (with whom he won the Jupiler League in 1975), and Lierse S.K.. Boskamp was furthermore voted Belgian Golden Shoe winner in 1975. He was part of the Dutch team for the 1978 FIFA World Cup, making one substitute appearance against Scotland.
Later Boskamp became a manager and coached Belgian clubs Lierse S.K., Verbroedering Denderhoutem, K.S.K. Beveren, K.V. Kortrijk, R.S.C. Anderlecht, K.A.A. Gent, and K.R.C. Genk, Georgian side FC Dinamo Tbilisi and also the Georgia national football team. After coaching Al Wasl FC of UAE and Kazma Sporting Club of Kuwait in the Middle East, he became manager of English side Stoke City for the 2005–06 season. He was then briefly the coach of Standard Liège in 2006.