Both Riske and Bencic went into the WTA International hard-court showpiece in China looking for their first Tour title, and the former came out on top, winning 6-3 6-4.
Swiss teenager Bencic was fancied to become the youngest Tour winner since Tamira Paszek of Austria, who was 15 when she won the Slovenia Open in 2006.
However, the third-seeded 17-year-old came unstuck against the American sixth seed.
Riske secured an early double break in the first set to quickly move into a 4-1 lead and, although Bencic struck back in the sixth game of the opener, the 24-year-old seized the initiative in the match by breaking for a third time.
Bencic's struggles continued in the second set, too, as Riske broke in game four to put herself on course for victory.
The Canadian got herself back into the match by breaking back, but Riske was not to be denied - breaking yet again when 5-4 up to seal her first Tour triumph.