Mabry was McGwire's assistant this past season.
McGwire, who held the St. Louis job for three seasons, is expected to become the Los Angeles Dodgers' batting coach, the St. Louis Post-Dispatch reported. The newspaper said McGwire is credited with helping develop young Cardinals hitters such as Allen Craig, David Freese and Matt Carpenter.
The Cards also promoted Blaise Ilsley to bullpen coach after five years as pitching coach for the club's Class AAA affiliate in Memphis.
St. Louis extended offers to bring back pitching coach Derek Lilliquist, bench coach Mike Aldrete, third base coach Jose Oquendo and first base coach Chris Maloney.
St. Louis finished 88-74 and in second place in the National League Central.