Hamilton was outrighted to Triple-A Jacksonville on Friday, Christina De Nicola of MLB.com reports.
Hamilton's contract was selected by the Marlins at the beginning of July, and he hit .077 with nine runs and seven stolen bases over 20 games with the major-league club. However, he'll lose his spot on the 40-man roster as part of moves to clear space for the returning Jon Berti and Brian Anderson, who were reinstated from the injured list Friday.