Tampa Bay signed the shortstop for $3.825 million on July 2, 2017, the earliest a team could ink Franco. By the next season, he was the MVP of the rookie-level Appalachian League as a 17-year-old after batting .351 with 11 home runs and 57 RBI.
He kept up the torrid pace in 2019, hitting .327/.398/.487 (batting average/on-base percentage/slugging percentage) between the Class A and Class A Advanced levels. But minor league season was canceled in 2020, forcing Franco and other minor leaguers to alternate training sites where they could spend time with big league players, or those closer to the show.