Carlo Ancelotti's side were in Seoul for the game, as they look to prepare for another World Cup bid next summer.
Casemiro captained the Selecao, with he and Cunha influential during a one-sided affair that yielded five goals without reply for the South Americans, who were mesmerising at times with their slick passing moves.
Brazil only took 13 minutes to move into the lead, as a slide-rule pass by Newcastle United's Bruno Guimaraes was tucked home by Chelsea youngster Estevao.
Casemiro claimed his assist four minutes before half-time, when Vinicius Jnr nudged the ball back towards Rodrygo, who cleverly left it for our no.