Garcia's immediate task will be to oversee pre-season training. The 40-year-old will take up his new post on Thursday morning.
He said, "I am delighted to have the opportunity to work in English football for the first time. Brighton & Hove Albion is one of the most exciting and progressive clubs in the country."
Chairman Tony Bloom welcomed Oscar to the club, saying, "We are delighted to have Oscar here to help us prepare for the new season and plan what promises to be another exciting campaign for the club."
In an illustrious playing career Garcia played for Barcelona and Valencia amongst others, before stepping into coaching as youth coach at the Nou Camp.
His first senior role was as manager of Maccabi Tel Aviv, and in his first season at the club guided the Israeli side to their first league title win in a decade.