Casali signed a one-year contract with the Giants on Wednesday, Andrew Baggarly of The Athletic reports.
Casali has spent all season with the Cubs' Triple-A affiliate, where he slashed .362/.489/.551 with 11 RBI across 88 plate appearances. He'll now return to San Francisco on a big-league contract to give the Giants depth behind the plate while Patrick Bailey (concussion) and Tom Murphy (knee) are sidelined. Blake Sabol will likely remain the primary option to start at catcher, though Casali could get the nod whenever the Giants are matched up against a left-handed starter.