Alves delighted with new deal
The new deal will keep the 27-year-old with the reigning Spanish champions until 30 June 2015.
"Being at the club for so many years is a dream," Alves, who joined Barça from Sevilla in 2008, told reporters in Brazil.
"I'm playing at one of the world's most desired teams, which is making history. The most important thing is that I'm happy and I want to make the most of it. It is a privilege and a joy to be here."
Alves is currently with the Brazil squad ahead of this weekend's international friendly against Scotland in London.