Ryan joins the Saints after spending the last two seasons running the Dallas Cowboys' defense.
"I am excited and thrilled to be joining the New Orleans Saints," Ryan said. "I have had the opportunity to get to know (head coach) Sean Payton and his staff a bit better recently and I am excited about joining the team."
In Ryan's first season (2011) with the Cowboys, the unit improved from 23rd to 14th in the NFL.
"Rob is enthusiastic about joining our team and getting right to work," Payton said.
Additionally, Ryan has served as the defensive coordinator for Cleveland (2009-10) and Oakland (2004-08).
The Saints also added Stan Kwan to the coaching staff, naming him an assistant special teams coach.
