"Jerry has a number of qualities that I think are assets for this role: he played the game, he coached a position group and he has coordinating experience," Munchak said in a statement released by the team. "I respected him as a player and coach, and he was someone that I knew right away that I wanted to talk to about the position.
"It was evident to me during (the) interview process that he will fit well with us -- he is familiar with our system and the type of players that we have on the roster. He is a great teacher and a great person, and I think the players will respond well to his style."
Gray was hired by Texas, his alma mater, to be defensive backs coach and assistant head coach to Mack Brown last month. He was due to make $425,000, but the Titans job meant at least doubling that for this season.
Gray said in a statement that he knows the timing of this move isn't ideal.
"But this was something that I couldn't turn down," said Gray, who played with Munchak during the 1992 season for the then-Houston Oilers.
Gray flew into Nashville on Friday to interview for the Titans' job and remained in Tennessee on Saturday, a league source told NFL Network insider Jason La Canfora.
"I am excited to have this opportunity," Gray said in the Titans' statement. "I have known Mike for a number of years, and if he is a head coach like he was a player or a position coach, we are going to be in great shape, because he has had so much success (in) everything he does. I am looking forward to really getting to know our personnel on defense and creating a defense that takes advantage of our strengths.
"I am an old-school guy that likes to get after the opponent, but you also have to have the players to (do) that -- you can't force those things. Our defense will fit what we can do well."
A two-time All-American at Texas, Gray was a four-time Pro Bowl pick during his nine NFL seasons with the Los Angeles Rams, Oilers and Tampa Bay Buccaneers. He started his coaching career with the then-Tennessee Oilers in 1997 as defensive quality control assistant when Munchak was promoted to offensive line coach.
Gray left in 2001 with Gregg Williams for Buffalo as defensive coordinator through 2005. Gray's Bills defenses in 2003 and 2004 ranked second in the NFL in each season for yards allowed. Both defenses ranked in the top 10 in points allowed. In 2004, the Bills led the NFL with 39 takeaways and were fifth in red-zone defense.
Gray coached the secondary in Washington between 2006 and 2009 before moving to Seattle for the 2010 season.
Munchak was announced as Fisher's replacement Monday, and he has spent the week shaping the staff that will work beside him in 2011. He fired offensive coordinator Mike Heimerdinger and two other assistants Tuesday and hired friend and former teammate Bruce Matthews to coach the offensive line Thursday. Matthews had agreed to, but not signed, a two-year contract with the Houston Texans.
Munchak has several openings left to fill including offensive coordinator, running backs assistant, defensive line and a couple of other assistants.
The Associated Press contributed to this report.