Park, who trailed Ciganda by two shots coming into Sunday's final round, forged into the lead on the 14th hole when the leader faltered with a bogey.
Ciganda -- seeking her first career victory -- added a double-bogey on the next hole, then bounced back with a birdie on the 18th to once again grab a share of the lead.
Top-ranked Park answered with a decisive birdie, draining an 8-foot putt on the last hole at Las Colinas Country Club to secure her sixth career LPGA Tour victory and third of the season.
Park finished at 4-under 67, ending the tournament at 13- under 271.
Ciganda settled for a 70, finishing one shot behind at 12-under 272.