The Catalan giants have now 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.
Blaugrana director Xavier Vilajoana confirmed last month that there was an agreement in place to complete a deal but there has yet to be an official announcement.
Barcelona were happy to pay the initial €1m for the deal earlier this year but then had to delay the confirmation due to a disagreement on the restructuring of the payment schedule.
However, that is not expected to force the deal to collapse, with Barcelona set to secure a majority ownership transfer, with Sao Paulo retaining a 30% stake in the highly-rated forward.
Maia has impressed for the club’s underage sides, as well as the Brazilian Under-16 and Under-17 sides.
He joined Sao Paulo as a 14-year-old and he scored 30 goals in 36 appearances during the 2018 calendar year and hit 21 the following year.