Janssen played professional football from 1982 to 2000 with, in chronological order, NEC, Fortuna Sittard, PSV, Kortrijk, again Fortuna and finally again with NEC.
Janssen's career in professional football spanned from 1982 to 2000, including NEC, Fortuna Sittard, PSV, Kortrijk, Fortuna, and finally NEC once more.