The Diamondbacks selected Smith's contract from Triple-A Reno on Saturday.
Smith opened the season as the Diamondbacks' main designated hitter against right-handed pitching, but he slashed just .141/.236/.192 with two extra-base hits and six RBI across 89 plate appearances before being DFA'd in early July. With Reno, Smith hit .301 with a .925 OPS across 181 trips to the plate to earn another chance at the big-league level.