Arthur was man of the match in the second leg of the 2017 Copa Libertadores final against Argentine side Lanus
Barcelona have agreed an option to buy Brazilian midfielder Arthur from Gremio in the summer.
The La Liga leaders have first option on the 21-year-old, who will cost £26.6m plus £8m in additional fees if they decide to complete the deal in July.
Arthur has represented Brazil at Under-17 and Under-20 level, and helped Gremio win the 2017 Copa Libertadores.
A Barcelona website statement said he “stands out for his passing ability”.
It added: “Another of his qualities is his ability to lose his man, a factor that makes him a danger close to the opponents’ area.
“The Brazilian is excellent at protecting the ball and can come up with the final pass in the final third.”
Arthur started his career in 2008 for the youth team at Goias Esporte Clube before moving on to Brazilian top-flight side Gremio in 2010.
He progressed to the first team under former coach Luiz Felipe Scolari, and was called up to the full Brazil squad in September although is yet to make his debut.