The 31-year-old was presented to the media on Monday and becomes the second shot-stopper to arrive at Camp Nou this summer, with the Blaugrana having already acquired Marc-Andre ter Stegen from Borussia Monchengladbach.
Bravo - who was part of the Chile squad that were eliminated from the World Cup in the second round by hosts Brazil - admitted that compatriot Alexis Sanchez had played a part in persuading him to leave Sociedad for Catalunya.
"I thank Barca for believing in me. I'm proud, this is a wonderful chance I'm getting. I'm very motivated to defend Barca's colours,” he said.
“Alexis has talked a lot about Barca and he told me it's fantastic and that I should enjoy every moment here in every possible way.
"I think I'll feel comfortable with Barca's style. At national team, we play a similar system. Before being a goalkeeper, I was also a centre-back."
Bravo's recruitment will come as welcome news to Barcelona fans following the departures of Victor Valdes – who left his boyhood club after the expiration of his contract this summer – and Jose Manuel Pinto, who was not offered a new deal.
Bravo, who has spent the last eight seasons playing for Sociedad, came through Chilean outfit Colo-Colo's youth system, where he made his first-team debut in 2002 aged 19.