The 33-year-old Brazilian had earlier announced he would leave Barca as a free agent after eight successful seasons, during which he won 23 titles.
"Juventus Football Club can today confirm that Dani Alves has agreed terms on a two-year contract with the club until 30 June 2018 with an option for an additional year," Juventus said in a statement.
Alves arrived in Spain in 2002 and spent six seasons at Sevilla before joining Barca.
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He won three Champions League trophies, three European Super Cups, three Club World Cups and six La Liga titles with the Catalan giants.
Alves is Juve's second summer signing following the acquisition of Bosnia midfielder Miralem Pjanic from AS Roma.
Juventus, coached by Massimiliano Allegri, won their fifth successive Serie A title this year and lifted the Coppa Italia.
(Reporting by Adriana Garcia and Silvia Recchimuzzi; editing by Ed Osmond)
