Morton made a career-high 29 starts for Pittsburgh in 2011, going 10-10 after posting a 2-12 mark a year earlier with the Pirates. The right-hander's earned run average dipped from 7.57 in 2010 to 3.83 this past season.
For his career, Morton has compiled a 21-39 record with a 5.11 ERA in 79 starts and one relief appearance for Atlanta and Pittsburgh.
Morton had offseason surgery to repair a torn labrum in his left hip.
Morton, who came the the Pirates along with Jeff Locke and Gorkys Hernandez from the Atlanta Braves in a trade for Nate McLouth in 2009, made $441,000 in 2011.
Evan Meek, Jeff Karstens, Garrett Jones and Casey McGehee are eligible for arbitration and remain unsigned at this time.