Haenen had an unsuccessful debut in 1992 at the Barcelona Games, where he finished 45th and 35th respectively in the 100 m and 200 m backstroke.
At the 1996 Summer Olympics in Atlanta, Haenen swum the backstroke leg in the heats of the 4 × 100 m medley relay, before being replaced by Steven Dewick in the team that trailed the United States and Russia home in the final. Haenen did not compete in any individual events.