The Cardinals' two primary catchers from 2012 -- Yadier Molina and Tony Cruz -- will return, but the addition of Johnson will provide Cruz with some competition as he tries to again earn the job as Molina's backup.
Johnson, 30, spent the 2012 season with the Mets organization, though he only appeared in 17 Major League games. He played in another 45 Triple-A games before his season ended in August due to a torn left thumb ligament. The Mets removed Johnson from their 40-man roster in October and he elected to become a free agent.
Johnson broke into the Majors in 2007 with the Mariners. He caught there for parts of four seasons before spending one year with the Padres and another with the Mets. In 245 career games, Johnson has a .201 batting average.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.