Terms of the deal weren't announced, but MLB.com reported it is worth $5.75 million.
The 27-year-old right-hander was officially introduced at the Orioles' Sarasota, Fla., spring training camp after passing a physical.
Yoon, a three-time all-star and 2011 MVP in the Korean Baseball Organization, pitched nine seasons with the Kia Tigers. During the 2011 season, he led the KBO in wins (17), ERA (2.45) and strikeouts (178).
Last season, he split time between the starting rotation and the bullpen for Kia, going 3-6 with a 4.00 ERA in 30 games. Yoon owns a 73-59 career record with a 3.19 ERA over his pro career.
He helped lead South Korea to its first-ever baseball gold medal at the 2008 Beijing Olympics.