Barton has spent all seven of his Major League seasons with the A's, owning a .248 career average. He was hitting .143 with one home run in eight games this season.
"We made the decision for a number of reasons," A's manager Bob Melvin said. "For our sake, I'd like to see him clear waivers. But if he's picked up, he'd have to be brought up to the Majors."
Barton's career with the A's reached a crescendo in 2010, when he achieved career highs in average (.273), home runs (10), RBIs (57), walks (110), stolen bases (7), hits (152) and games (159).
"He did a nice job while he was here," Melvin said. "I know the numbers don't show that."
Rick Eymer is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.