"I chose the club because they showed a big interest in me and my goal has always been to play in the Premier League because it’s the biggest league in the world," Bernardo was quoted as saying on the south-coast club's official.
Manager Chris Hughton added: "He is a strong, committed defender who can play on the left or right, and so his versatility gives us good options at the back."
Brighton finished 15th last term in their first season back in the top flight since 1983, when they were FA Cup runners-up.
Bernardo joined Red Bull Salzburg at the start of 2016, playing 13 games as the Austrians retained their league title.
He moved to Leipzig at the end of that campaign and has played 49 times in the last two seasons, including three games in the Champions League and five in the Europa League.
Bernardo's father, also called Bernardo, played over 300 league games for Sao Paulo, Santos and Corinthians, and featured four times for Bayern Munich. He played 19 games for Brazil.
Brighton had already signed Romania striker Florin Andone (Deportivo La Coruna) and Nigeria international Leon Balogun, who joined on a free transfer after leaving Mainz, plus goalkeeper Jason Steele (Sunderland).
($1 = 0.7565 pounds)
(Reporting by Ken Ferris; Editing by Hugh Lawson)
