Manager Torey Lovullo confirmed Walker (finger) will start Wednesday's game against the Tigers.
Walker has been sidelined since May 21 with a blister issue, but he was able to progress steadily through his rehab with no issues and is expected to be activated from the disabled list ahead of Wednesday's contest. The 24-year-old, who compiled a 3.46 ERA and 46:18 K:BB across nine starts (52 innings) before landing on the DL, will duel with Jordan Zimmerman in his first game back. Randall Delgado is expected to lose his rotation spot upon Walker's return.