The Diamondbacks selected Loaisiga's contract from Triple-A Reno on Wednesday.
Loaisiga had been attending camp as a non-roster invitee but secured his place in Arizona's Opening Day bullpen after posting a 9:2 K:BB while permitting four earned runs and allowing nine hits over eight innings. He'll likely begin the season in a middle-relief role for Arizona but could quickly work his way into higher-leverage spots if he performs well early on.