Gavin Moynihan chipped in for Ireland on the play-off hole to set up a final against France at the GolfSixes.
After ending the hopes of England Women in the quarter-finals, Moynihan and Paul Dunne were level at 1-1 after six holes in their semi-final and South Korea were the favourites after the tee-shots on the extra hole at Centurion Club.
Enter Moynihan, who holed his chip to heap the pressure on Jeunghun Wang and the three-time European Tour winner could not make his birdie.
The French team of Mike Lorenzo-Vera and Romain Wattel enjoyed a more straightforward victory against Australian pair Sam Brazel and Wade Ormsby, winning 3-1 as they took the first, third and fourth.
After Saturday's group stages, we were into the knockout with the same innovative format seeing the teams playing match play greensomes over six holes.
Both South Korean tee-shots missed the green on the first but Wang chipped in to pile the pressure on Dunne, who holed his putt to keep it 0-0.
A poor chip on the second led to a South Korean bogey and a 1-0 Irish lead but with both teams missing the green on the fourth and only the South Koreans getting up and down for par, the match was guaranteed to go up the last.
Soomin Lee hit the closest tee-shot on the fifth but Dunne made a birdie to put the pressure on Wang who followed him in, with Lee then stepping up and holing a five-foot birdie putt on the sixth to send us to the play-off hole.
France took the early initiative as Wattel hit a brilliant tee-shot on the first and Lorenzo-Vera holed from three feet for a 1-0 lead but an excellent Wade Ormsby approach on the next helped Australia level things up.
The French then took advantage of the par five third and when Australia bogeyed the fourth, the match was on a knife-edge.
Wattel's tee-shot to inside a foot on the fifth left Australia needing a hole-in-one and while Ormsby put his first to tap-in range, it was only good enough for a half.
The final is a repeat of Saturday's Group C clash that France won 2-1.
