The Brazil global will join Juve for 72m euros (£66m) - with 10m (£9m) in add-ons.
Arthur joined the club from Gremio in 2018 and has turned out 72 times in total for the Camp Nou side, including 28 appearances in all competitions this season, during which he has scored all four of his goals for the club. Of late, though, it emerged that the deals for the two players will be separate, with the Bianconeritouted to pay Barcelona €80 million to secure the services of the 23-year-old.
"FC Barcelona and Juventus FC have reached an agreement for the transfer of player Arthur Melo", Barcelona's statement read.
The initial reports suggested that Arthur would join Juventus as part of a swap deal which would see Miralem Pjanic join Barcelona. He passed his medical examination and the transfer was completed.
This is being done in a way - prior to June 30 - so that the transaction can be in this year's accounts, which was essential for Barcelona as they look to balance their books. However, Arthur eventually gave in to the pressures of Barcelona, more driven by the need to balance the numbers than disenchanted by his mediocre performance, the other big weight on the scale.
In any case, Arthur will not be seen playing in a Juventus shirt until next season.
Initially the former Gremio midfielder had reservations about leaving Barcelona, but finally, after seeing how much the Blaugrana were pushing him towards the exit door, he chose to depart the club.