Jenkins, 25, was a first-round pick when he was the 20th overall selection in the 2009 MLB First-Year Player Draft. Jenkins was 5-9 with a 4.96 ERA at Double-A New Hampshire, but in his last 10 starts he was 3-3 with a 3.84 ERA.
There was no immediate word from the Blue Jays on how Jenkins would be used.
Jesse Chavez was designated for assignment to make room for Jenkins. Chavez, a 28-year-old right-hander had an 8.44 ERA in nine games with the Blue Jays. He picked up his only victory of the season with a scoreless inning in the 10th inning on Saturday.