The Catalan giants have paid an additional €3.5m deal to complete the transfer after holding a €1m deposit on a player who has yet to play a senior match for the Brazilian club.
Maia is known as a pacey forward with strong finishing ability and an eye for a pass but it is no doubt unusual that he is yet to play a professional game in his home nation before securing a switch to European football.
Barcelona transfer news has been dominated by their pursuit of Inter striker Lautaro Martinez and the arrival of Miralem Pjanic from Juventus, with the club extremely busy in restructuring their squad.
However, the Brazilian will go into their B side for next season with the details of the arrangement outlined in a report by Marca.
The player has signed a five-year contract with the Blaugrana and it is probable that the club will listen to loan offers.