The Reds plan to have him make his first start of the season on Friday against the Oakland Athletics in the opener of a three-game series.
They expected DeSclafani to be their opening day starter, but he strained an oblique during spring training and has been sidelined. He was close to returning last month but had a setback.
"I definitely didn't think it was going to take this long, but I didn't want to try it until I was 100 percent," DeSclafani said Tuesday. "I'm definitely excited to finally make my debut. I'll have to work on not getting too excited."
He'll take the place of Jon Moscot, who was optioned to Triple-A Indianapolis after getting hit hard in his last couple of starts. Moscot spent time on the disabled list with a strained muscle in his left side. In two starts since his return, he gave up 12 runs and six homers in 5 2/3 innings.
Manager Bryan Price had considered moving one of his patchwork starters into the NL's worst bullpen when DeSclafani returned, but he decided against it with Moscot.
"He hasn't pitched well," Price said. "He's getting hit hard and that doesn't fit any better in the bullpen than it does in your rotation."
The Reds have four starters on the disabled list, including DeSclafani. They're hoping to get Raisel Iglesias and Michael Lorenzen back this month, and Homer Bailey back in July. Bailey is the most experienced member of the rotation, but he had Tommy John surgery 13 months ago and suffered a setback in his rehabilitation last month.
The Reds also called up outfielder Steve Selsky from Louisville, giving them another player available off the bench for their series beginning Tuesday against the St. Louis Cardinals. Jordan Pacheco was limited by a sore shoulder that interfered with his swing but wasn't serious enough for the disabled list.