He becomes the club's fourth signing ahead of the 2018-19 campaign with Chris Hughton already strengthening his hand with the arrivals of Jason Steele, Florin Andone and Leon Balogun.
"We're delighted to welcome Bernardo to the club," Hughton told the club's website.
"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.
"For a young player he already has good experience, having played in the Bundesliga, the Champions League and the Europa League.
"He is a good character and speaks numerous languages, and I'm sure he will fit in well with the rest of the squad."