The 20-year-old has put to pen to paper on a five-year deal that will keep him at the BayArena until 2019.
Wendell becomes the latest in a line of Brazilians to play for Leverkusen by following in the footsteps of World Cup winners Paulo Sergio and Lucio and current Gremio captain Ze Roberto.
And Wendell revealed that Ze Roberto's advice had played a big part in his decision to join the Bundesliga outfit.
"Bayer Leverkusen continues to enjoy an excellent reputation in Brazil," Wendell told the club's official website.
"Ze Roberto, who played many years with Bayer, advised me to embark on this path.
"He has raved about his time with Leverkusen in the highest tones."
Wendel has made just 17 appearances for Gremio since joining in June 2013, but Leverkusen sporting director Rudi Voller is confident that the left-back can have an immediate impact.
"Wendell is a huge talent that can help us immediately," Voller added.
"We are sure that he can continue the great tradition of top Brazilian players at Bayer Leverkusen."
