Since August 13, 2023, Franco has been placed on administrative leave due to an investigation about allegations of relationships with underage girls in the Dominican Republic.

On September 22, the Rays added Franco to their pool of players who would be eligible to play in the Major League Baseball postseason.

[14] Instead, he played in the Dominican Winter League in the 2020-21 offseason with Leones del Escogido, batting .350/.435/.500 in 23 at-bats.

The Rays invited Franco to major league spring training in 2021,[15] but he did not make the team, and began the season in Triple-A with the Durham Bulls.

[17] On June 20, 2021, the Rays announced that Franco would be promoted to the major leagues, prior to the team’s series against the Boston Red Sox.

[21] In the game, Franco recorded his first career hit, home run, and RBI on a three-run shot off of Red Sox starter Eduardo Rodríguez in the fifth inning.

[23] On August 25, Franco reached base safely for the 26th consecutive game, setting a record for the longest run by a player under 21 years old since 1961.

Franco became the youngest player in Tampa Bay Rays franchise history to have a multi homer game, doing so at age 21 and 52 days old.

The league stated the administrative leave "is not disciplinary under the Joint Domestic Violence, Sexual Assault and Child Abuse Policy" according to MLB.

With Willy Adames and Jeremy Peña at shortstop, he instead played second base, splitting time with Ketel Marte.

[43] On November 10, while awaiting trial, Franco was arrested again in San Juan de la Maguana after an altercation in which guns were drawn.