Holding a one-point advantage over their rivals, Korea Republic required just a draw to advance into the knockout stage.
A tentative opening was enlivened in the early stages by Thais Guedes delivering a well-hit free-kick which cannoned back off the crossbar.
Korea Republic remained largely conservative with their attacking threat, although looking dangerous at times on the break.
Brazil endured another piece of bad luck just prior to the interval, with Ketlen pushing the ball home from close range only for the goal to be ruled out of or offside.
Again Brazil started with more intent and Thais saw her header palmed over by goalkeeper Jeon Haneul.
Brazil, however, were not rewarded for their endeavour and were caught on the counter as Lee Sodam found the perfect pass to release Eunha, who coolly finished, leaving Brazil hunting two goals in the final 16 minutes.
The same pair combined on 82 minutes to double the advantage, with Sodam crossing for Eunha to smartly volley home for her second of the match and third of the tournament.
"With the performance of players today it was not possible only to attack with short passes," said Korea Republic coach Jong Song Chon.
"They were able to play with flexibility for today’s match. They understand they have to be more flexible [in their approach]. Korean football normally asks for collective style of play, and not long passes."