The Chicago Tribune reported the news earlier Monday.
The Bears also hired Sean Desai as a defensive quality control coach and Dwayne Stukes as assistant special teams coach.
Selected by Chicago in the sixth round out of the University of Louisiana at Monroe, Harris spent two stints with the Bears. His first lasted two seasons before the club traded him to the Carolina Panthers. Harris rejoined the Bears in 2010 through another trade with the Panthers.
Harris rewarded the Bears that season with 96 tackles and a career-high five interceptions, which tied for third in the NFL among safeties, on his way to earning All-Pro recognition.
With the Jaguars, Harris played under recently hired Bears defensive coordinator Mel Tucker.
On Jan. 18, Harris had already made up his mind about retiring and was looking for a way to break into the coaching field in the NFL. Harris’ familiarity with the Bears and Tucker likely played a role in the former safety making his return to the team.
In 101 career games over eight years, Harris intercepted 16 passes, in addition to posting 365 tackles. Harris also forced 14 fumbles and broke up 39 passes.