The midfielder had been hoping to move away from Liverpool this summer and Inter Milan had been favourites to land him.
The 26-year-old told Barca TV: “The truth is it’s a dream, it’s a great joy and a reason to be proud for me and my family because of what it all means, for everything they’ve achieved in the last few years.
“As well as being a great team they are also a great group of people. Hopefully things will go well from the start.”
He added: “I’ll give the same as I always have for all the teams I’ve played for; sacrifice, desire and I will try to do things as well as possible and help all the time.
“It’s a great club with great players and I will try to adapt as quickly as possible.”
