Hull, 19, had a share of the lead going into the final round but struggled with two bogeys to finish on 14 under par.
It left her four shots behind the winner, South Korea's Kim Hyo-joo, who had a superb seven-under final round of 66 for a two-shot victory.
She finished ahead of compatriot Kim Sei-young, Sweden's Anna Nordqvist and American Stacey Lewis.
It is her third career LPGA title after wins in the 2014 Evian Championship and last year's LPGA Founders Cup.
A final round of 71 ended England's Charley Hull's hopes of victory at the Pure Silk Classic in the Bahamas.