The 26-year-old, who joined the tour in 2024, finished at 17-under with a group of home players just behind her and was doused in champagne after sealing a career-changing victory.
Yoshida started the day four shots off the pace but made a fantastic start to her final round with an eagle and three birdies in her first seven holes at Pine Beach Golf Links.
Perhaps sensing a maiden LPGA victory, Yoshida stumbled with a bogey at the 15th, birdied the 17th and then bogeyed the final hole.
But with overnight leader Ryu Hae-ran also dropping a shot at the 18th, Yoshida's final-round four-under-par 68 was enough to get the job done.
Home players Choi Hye-jin and Ryu were tied second on 16-under, with fellow South Koreans Kim Min-sol and Kim Hyo-joo another shot back.
It was more agonising disappointment for Choi, whose wait for a first LPGA win goes on.
She was also runner-up by one stroke last week in Shanghai, on that occasion behind home player Yin Ruoning.
