Germán was signed by the then Florida Marlins as an international free agent in 2009. He made his professional debut in 2010 for the Dominican Summer League Marlins. Germán played the 2014 season with the Greensboro Grasshoppers, pitching to a 9–3 win-loss record with a 2. 48 earned run average (ERA) and 113 strikeouts. In July he was selected to play in the All-Star Futures Game and recorded two strikeouts in the game.