Horton joins the club from the Cleveland Browns after just one season at the team as he links up with old boss Ken Whisenhunt, who was named the head coach of the Titans last week; the duo were at the Arizona Cardinals together.
"Really excited to have Ray Horton joining our staff," Whisenhunt told the club's official website. "His body of work speaks for itself over the last few years as a coordinator and a position coach.
"Not only was he a good player in the league for a number of years, but he has transferred that into becoming a very good NFL coach."
Horton's defense was ranked ninth in the NFL in the 2013 season.