Barnhart signed a minor-league contract with the Diamondbacks on Tuesday and received an invitation to major-league spring training.
Barnhart slashed .202/.285/.257 with nine RBI across 123 plate appearances with the Cubs last season before being DFA'd and finishing the year with the Dodgers' Triple-A affiliate. With Gabriel Moreno virtually locked in as Arizona's everyday catcher, Barnhart will compete with Jose Herrera in the spring for the backup job.