Molina joins Bobby Jones, who was promoted from Triple-A Round Rock to be the Rangers' assistant hitting coach.
Molina, 39, spent last season as the assistant hitting coach for the St. Louis Cardinals, his first stint as a coach since ending his 13-year major league career with the Rangers in 2010.
Molina, acquired on July 1 of that season, helped lead the Rangers to the World Series for the first time in franchise history. He batted .293 with two homers and eight RBIs in that postseason run.
Perhaps Molina's most memorable moment as a Ranger was hitting for the cycle at Boston's Fenway Park on July 16, 2010, chugging to third for a triple to complete that cycle. He also had a grand slam in that game.
Molina was a career .274 hitter with the Angels, Blue Jays, Giants and Rangers and won two Gold Gloves. He was the starting catcher for the Angels' 2002 World Series run.
Jones, 64, will make his third big league coaching stint for Texas. He was on Johnny Oates' staff in 2000 and 2001 and coached first base in 2006 for Buck Showalter. Next season will be his 27th as a coach or manager in the Rangers organization.
The club also announced that trainer Jamie Reed is now senior director of medical operations and Kevin Harmon has been promoted to head trainer. Reed will oversee all medical aspects of the club, including the farm system.