Initially part of the first-team plans for Juventus prior to the start of the 2013–14 Serie A season, Marrone was sold to newly promoted Serie A side Sassuolo on 2 September 2013 on a co-ownership deal. The deal served as an exchange for 50% of the contract of Sassuolo's Domenico Berardi, who joined Juventus on a co-ownership deal but remained at Sassuolo on loan for the 2013–14 campaign. Marrone's season with the "neroverdi" began well, but was ultimately hampered by injuries that limited the midfielder to just 15 league appearances. On 20 June 2014, the co-ownership deal was renewed between Sassuolo and Juventus, with Sassuolo retaining the playing rights for the player.