The Diamondbacks reinstated Montgomery (knee) from the 15-day injured list to start Tuesday against the Royals, Alex Weiner of ArizonaSports.com reports.
The veteran left-hander has been on the shelf nearly a month due to right knee inflammation and is returning to Arizona's rotation without a minor-league rehab assignment. Montgomery threw 56 pitches in a simulated game Thursday and will likely face some minor workload limitations in his first couple starts back with the Diamondbacks.