The decisive moment came in the second half when Maseko brought the ball onto his left foot inside the penalty area before drilling his effort through the legs of Jens Castrop and inside the near post.
The victory lifted South Africa to second place in Group A behind Mexico and booked a last 32 meeting with Canada in Los Angeles on Sunday.
South Korea enjoyed more possession but struggled to create meaningful chances, with Oh Hyeon gyu’s tame header and an early effort from Lee Kang in among their few opportunities.
South Africa looked the more dangerous side on the counter attack throughout and created the better chances, producing a disciplined and organised display that ultimately earned them a deserved victory.
The result also extends the tournament for South Africa coach Hugo Broos, who has already announced he will retire at the end of the competition.
South Africa had not appeared at a World Cup since hosting the tournament in 2010 and had previously finished third in every group stage campaign. Their latest victory marks a historic breakthrough as they advance to the knockout rounds for the first time.
South Korea, meanwhile, must now wait to discover whether they will progress as one of the competition’s best third placed teams.
