The left-handed Ohori, ranked 20th in the world, bounced back from a set down to beat her fifth-ranked Thai opponent 16-21, 21-17, 21-11.
Ohori, 23, will go up against An Se-young of South Korea later today (Jan 25) at the Indoor Stadium Huamark in Bangkok.
Former world champion Carolina Marin, who lost the Indonesia Masters title to Ratchanok, also moved through after dispatching Japan’s Sayaka Takahashi 21-9, 21-16.
The Spaniard will meet top seed and world number three Akane Yamaguchi of Japan today.
In the men’s singles, Hong Kong’s Angus Ng Ka Long battled past Korea’s Heo Kwang-hee in three sets to win 21-16, 13-21, 21-11.
He now faces China’s Shi Yu Qi in the semi-finals today.
But Thai fans can still root for 18-year-old Kunlavut Vitidsarn, who will take on Japan’s Kenta Nishimoto in the other semi-final.
The Thailand Masters is the second competition this month to not feature men’s world number one Kento Momota after the Japanese superstar was injured in a car crash that killed his driver and left him with minor injuries in Kuala Lumpur (see story here).
He is expected to return to action at the All England Championships in March.