The Rangers selected Ross's contract from Triple-A Round Rock on Saturday.
Ross has put up a 2.92 ERA and 1.32 WHIP through 12.1 innings at Round Rock since signing a minor-league deal with the Rangers in late May. His strong showing will earn him another chance in the majors, though he'll likely be limited to low-leverage work after allowing eight earned runs in 3.2 frames with Arizona earlier this year. Luis Curvelo was optioned to Triple-A to free up room on the active roster, and Michel Otanez was DFA'd to clear a 40-man spot.