Ciganda offset a pair of bogeys with eight birdies at Sentosa Golf Club to finish even with Park (69) at 9-under 135.
Azahara Munoz was in sole possession of third place, two strokes back, after a 67 that featured six birdies against a lone bogey.
Ciganda, who is bidding for her first LPGA victory, got off to a shaky start with a bogey on the par-4 first hole. But she quickly recovered with two straight birdies on Nos. 2 and 3 that set her on the way to the day's lowest score.
Overnight co-leader Yani Tseng struggled with her game and finished with a 75 for a share of 17th place.