Chelsea bag Luiz from Benfica
"Benfica informs it has reached a deal with the Premier League's Chelsea Football Club Limited, to sell David Luiz on a permanent basis for 25 million euros," Benfica said in a statement.
Chelsea's Serbian midfielder Nemanja Matic will move to Benfica as part of the deal, the Portuguese club added.
Luiz, 23, had a contract with Benfica that ran until 2015 and is seen as one of the most promising defenders in Europe.
He arrived in Lisbon from Brazil in 2007 and was a key member of the Benfica side that last season clinched the Portuguese Premier League title for the first time in five years, missing only one of 30 league matches.
His performances earned him a debut call-up to the Brazil squad for a friendly against the United States in August. He also played against Iran and Ukraine in October and is in the squad for the February 9 friendly in France.