 On 5 July 2018, Boateng signed with Sassuolo on a three-year deal.Boateng joined Spanish La Liga club Barcelona on 21 January 2019 on loan until the end of the 2018–19 season, with the club holding an option to sign him permanently for a €8 million transfer fee.He has joined the Catalan side to serve as a backup for Luis Suárez after Munir El Haddadi was sold to Sevilla.