The Marlins claimed McMillon off waivers from the Royals on Friday.
McMillon has spent all of this season at the Triple-A level, where he has posted a 6.53 ERA in 30.1 appearances. At his best, McMillon has shown late-inning caliber stuff, but he has dealt with arm injuries and his stuff was diminished this season. He'll head to Triple-A Jacksonville, where he represents relief depth for Miami.