General manager Ray Shero announced the hiring Tuesday.
The 37-year-old Clemmensen joins the staff after a 14-season playing career, including eight seasons over three stints with the Devils. He played 27 games with Albany (AHL) and three contests with New Jersey last season.
Clemmensen played 191 career NHL games with New Jersey, Toronto, and Florida, posting a 73-59-24 mark with seven shutouts and 2.79 goals-against average. He was 32-19-6, four shutouts with New Jersey, including a career-best 25 wins in 2008-09.
Clemmensen played four seasons at Boston College, where he helped the Eagles to the 2001 Hockey East and NCAA Championships.
Shero says Clemmensen fits well with young goalies because he's played at every level.