Morillo, a hard-throwing 25-year-old, was designated for assignment by Colorado before appearing in a game this season. The Dominican Republic native has registered just 8 2/3 innings in his short Major League career while giving up 11 runs. He notched a 5.28 ERA while making 52 appearances for Triple-A Colorado Springs last season.
Morillo will take the roster spot of Humber, who gave up six runs in 4 1/3 innings with the Twins this season. The 26-year-old, who is one of four players received by the Twins in the Johan Santana trade, has given up 18 runs in 25 innings during parts of four big league seasons.
Humber and Morillo are both out of Minor League options.
Alden Gonzalez is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.