Ji-Yai Shin and Eun-Hee Ji were comfortably in the lead after nine holes, but Rosales and Delasin had five birdies and finished at 18-under 198 at the Gary Player Country Club.
Taiwan and Japan shared third place at 203.
Juli Inkster and Pat Hurst of the United States had six birdies and a bogey for a final round 67. Their 208 gave them a share of 10th with Scotland.
Delasin sealed the win with a 15-foot putt for birdie on the par-5 18th, after she had pulled her drive to the right of the fairway. She threaded her second shot close to the trees onto the fairway, and dropped her third to set up the putt.
'I had an angel with me on that (putt),' Delasin said. 'I had no fear. I just crossed my fingers and hit it.'
Korea went into the final hole needing an eagle to get back into the match. Shin's second shot aimed straight at the pin but it veered right and bounced off a rock in the water surrounding the island green. It landed 30 feet from the flag.
Shin finished with a birdie, Korea's second on a homeward nine against six for the Philippines.
It was the reverse for the opening nine holes. Shin had an eagle 3 on the fifth and a birdie on the par-4 sixth, to pressure the Philippines, who birdied the first and third holes.
Gwladys Nocera and Virginie Lagoutte-Clement of France shot 67 to finish fifth, while South Africa, Canada and Wales shared sixth.