Stephenson allowed three runs (none earned) on two hits in his return, striking out three and walking two.
"Physically, I felt great," Stephenson said. "Some things felt rusty, but physically it was fine."
Stephenson was on a tight pitch count that limited him to between 60-65 pitches. He said he expects to return to his normal workload in his next start.
Before the injury, Stephenson was having an excellent first year in full-season ball. He is 5-3 with a 2.82 ERA and has struck out 88 batters and walked 19 over 70 1/3 innings.
Stephenson, ranked No. 41 on MLB.com's Top 100 prospect list, has an impressive array of pitches, including a fastball that has touched 100 mph and a promising slider and changeup. He said the key to his success this season has been his command.
"The biggest thing for me was getting ahead in the count," Stephenson said. "Being able to throw all three pitches for strikes."
Teddy Cahill is a reporter for MLB.com. Follow him on Twitter at @tedcahill. This story was not subject to the approval of Major League Baseball or its clubs.