The sixth-ranked Indian has been in imperious form all week in the Chinese city of Guangzhou and made it a fourth victory with a bruising defeat of Thailand's Ratchanok Intanon.
The 23-year-old Sindhu, renowned for her never-say-die attitude, needed all her resolve to finally see off Ratchanok 21-16, 25-23 in a captivating semi-final.
"I'm quite happy with my fitness level this week. It's too bad that I made bad decisions on some shots. It's been a great year for me though," said Ratchanok after completing her last match of the seasson.
Thai players also lost in the mixed doubles as Dechapol Puavaranukroh and Sapsiree Taeratanachai were sent packing 21-19 14-21 12-21 by Chinese Zheng Siwei and Huang Yaqiong in the semi-finals.
In the other last-four clash on Saturday in the women's draw, Okuhara, a place above Sindhu at five in the world, emerged from an all-Japanese clash against Akane Yamaguchi.
Okuhara defeated her compatriot, who is ranked two in the world, 21-17, 21-14.
The men's semi-finals were due to take place later Saturday.
Japan's world champion Kento Momota plays Son Wan-ho of South Korea and surprise package Sameer Verma of India takes on Shi Yuqi of China.