Two of Chafin's teammates are also scheduled to be activated Tuesday -- right-hander Rubby De La Rosa and catcher Chris Herrmann. Both have been with Triple-A Reno, whose season came to an end Monday.
The D-backs will also have at least one other promotion that the club has yet to announce.
"The group will come up tomorrow," D-backs manager Chip Hale said prior to Monday's series opener with the Dodgers. "They're all flying tonight and should be activated tomorrow."
• Patrick Corbin has had some success pitching out of the bullpen the last few weeks, but Hale said the organization still regards the left-hander's future as a starter.
"I just think Patrick's arsenal of pitches, I just feel like he's more suited to start; I really do," Hale said. "I think he's got all the pitches and I think doing what he's doing right now is getting his confidence back."
Corbin is likely to get a start before the end of the season.
Steve Gilbert has covered the D-backs for MLB.com since 2001. Follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.