Marotta left Samp for Juve at the end of last season.
He reflected: "In eight years I experienced with Sampdoria an unforgettable time for a manager. When I arrived the club was close to Serie C, when I left they had gained qualification to the Champions League.
"This is thanks to the Garrone family and professionalism of the club. I'm excited, it's a page full of memories and emotions."