Initially drafted by the Angels in the first round in 2006, Conger spent the first five big league years of his career with them until being traded to the Astros before the '15 season.
Conger is the fourth veteran catcher signed by the D-backs this offseason, joining Jeff Mathis, Chris Iannetta and Josh Thole.
Mathis and Iannetta were signed to Major League contracts and are expected to team with Chris Herrmann to form a three-headed catching platoon.
Steve Gilbert has covered the D-backs for MLB.com since 2001. Follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.