Kliff Kingsbury acknowledged earlier this week there had been consideration of putting rookie defensive end Zach Allen on injured reserve, which would end his season.
The Cardinals moved past the consideration stage Wednesday, making the season-ending decision on Allen by placing him on IR with his lingering neck issue.
Replacing Allen on the roster is rookie defensive tackle Miles Brown, who the Cardinals promoted from the practice squad.
With Brown's promotion, along with the promotion of linebacker Pete Robertson and cornerback Chris Jones from the practice squad on Friday, the Cardinals had three open practice squad spots. Those were filled Wednesday with the additions of two former Cardinals in outside linebacker Vontarrious Dora and cornerback Sojourn Shelton, along with offensive lineman Ian Silberman.
Allen got hurt in Week 4 against the Seahawks, and suffered a setback in practice soon after that. The hope had been that he was going to be able to return following the bye.
"The big thing with Zach is the reps are so valuable as a rookie," Kingsbury said Monday.
Allen finished his rookie season with 8 tackles, with one tackle for loss.