The second-ranked South Korean star birdied the final two holes for a bogey-free, 8-under 64 and a three-stroke victory over Ciganda in cloudy conditions at tree-lined Club de Golf Mexico.
''It was definitely the putter. It was really good this week,'' Park said. ''I made a lot of birdies this week. It was a lot of fun today with Carlota playing so well. ... It was almost a perfect day today. I didn't make any mistakes, so I was able to focus on my game.''
Ciganda shot a 63. The Spaniard eagled the par-5 second hole and had eight birdies and a bogey.
''I did the best I could,'' Ciganda said. ''I putted really well today. I think that was the key. ... Inbee played unbelievable and she has lots of experience. She knows how to win.''
The former Arizona State player is winless on the LPGA tour.
Park finished at 18-under 270. She was making her first start since withdrawing in China two weeks ago because of a cyst on her left middle finger.
Tournament host Ochoa won 27 LPGA Tour titles. She retired in 2010.
''Winning this tournament is such an honor,'' Park said.
Park took the lead from top-ranked Lydia Ko in the Vare Trophy standings for season scoring average and moved within three points of Ko in the player of the year standings. Park earned $200,000 and is second on the money list with $2,570,096.
Ko skipped skipping the tournament to rest for her title defense next week in the season-ending CME Group Tour Championship in Naples, Fla.
South Korea's Sei Young Kim was third at 13 under after a 66.
So Yeon Ryu, also from South Korea, shot a 67 to finish fourth at 11 under.