The 21-year-old has been a key plater in the Arsenal team this season.
“My development since I joined back in 2006 has really pleased me, and I just want to build on last season’s performances,” said the Brazilian told the club’s official website.
“We have a hugely talented group of players here, and I am convinced that with everyone working together we’ll be able to achieve great things.
“It’s a special time to be part of this club and I’m delighted to have signed a new long-term deal.”
