Yoon joined his teammates in the clubhouse Friday after spending several days in Canada obtaining a work visa. He flew out of Sarasota on Sunday and was scheduled to return Wednesday, but his flight was canceled because of weather.
The 27-year-old Yoon agreed to a $5.75 million, three-year contract with the Orioles in mid-February.
He was both a starter and reliever in nine seasons for the KIA Tigers. He will pitch in relief against the Yankees.
Yoon says he wants to get his feel for pitching on a mound.
Asked if he might have the jitters Saturday, Yoon said he's nervous every time he throws. He said he'll "have those butterflies in my stomach, of course, but I'll be fine."