The Diamondbacks selected Feyereisen's contract from Triple-A Reno on Saturday.
Feyereisen has been great to start the season in Triple-A, surrendering just one earned run over 9.1 innings while striking out seven batters and walking two. He'll now head to Arizona to help provide bullpen depth with Joe Mantiply and Bryce Jarvis moving to the minors and A.J. Puk (elbow) moving to the IL.