Three-time Grand Slam winner Rybakina, the number one seed and defending champion, defeated the 13th-ranked Russian 6-3, 7-5.
Rybakina, who usurped Aryna Sabalenka as world number one in her US Open triumph in September, missed last week's Wuhan Open with a foot injury.
The Moscow-born Kazakh threatened to run away with the first set but struggled to put Shnaider away when serving at 5-3 up.
Rybakina twice double-faulted as she uncharacteristically saw an astounding 10 set points come and go.
The 27-year-old finally clinched the set at the 11th time of asking.
The hard-hitting Shnaider, 22, dug herself out of a hole on her own serve to hold at the start of the second set.
Now in the groove, Rybakina ramped up the pressure to break serve in the seventh game, then held for a 5-3 lead.
Rybakina served for the match at 5-4 but inexplicably crumbled with victory in sight and was broken to love, only to recover and immediately grab the break back.
She served for the match once more at 6-5 and this time made no mistake, sealing the deal on her second match point with a two-handed backhand down the line.
In the other semi-final, Fernandez defeated Marie Bouzkova 6-3, 7-5 as she chases a second title in as many months.
The Canadian world number 30 won her first title of the year in Singapore last month and had too much for the 26th-ranked Bouzkova of the Czech Republic.
After dominating the first set, Fernandez broke early in the second for a 2-0 lead, only for Bouzkova to hit back as both struggled on their serve.
The second set turned into an arm-wrestle before Fernandez prevailed in just under two hours when Bouzkova returned long.
