Vítor Roque was introduced to the Spanish media on Wednesday after joining Barcelona from Brazilian side Athletico Paranaense for a fee thought to be worth up to €61million (£52.2m, $66.9m).
Reports suggest the La Liga side will pay an initial €30m to Athletico Paranaense with another €31m due in potential bonuses.
The Brazilian striker has a buyout clause set at 500 million euros.
The 18-year-old has signed a seven-and-a-half year deal with the Spanish champions which is valid until June 2031, and arrives having already made a big impression in his native Brazil, having scored 28 goals in 80 games.
Xavi's side is currently fourth in the table, and face Las Palmas in La Liga on January 4th.