Zheng was a break down in the first set and saved set points in the opener, before the home favourite went on a tear to take it 7-5 in Beijing.
The former Australian Open finalist broke in the very first game of the second set, but just when the Russian looked like she would implode, Andreeva levelled proceedings at 1-1.
Cheered on by the home crowd, wildcard Zheng, who beat four seeded players to reach the final, regained her composure and broke at 4-4 after creating a slew of break points.
French Open champion Andreeva threatened to break back immediately but the home favourite held her nerve and closed out a 7-5, 6-4 victory in one hour and 42 minutes.
Zheng was down in 54th in the WTA rankings prior to the tournament but her remarkable triumph has seen her rise to 23rd in the world rankings while Andreeva has risen to third on the list.
"The feeling was incredible, two weeks here in Beining, in front of my home crowd is one of my dreams, especially playing against Mirra, such a great player," the new Beijing champ said.
"First of all, I want to say congratulations for this year, the Roland Garros you won, that was an amazing achievement. I never had a chance to say congratulations to you. Second congratulations for this week, reaching the finals. You're such a young player, very talented, and congrats to your team."
Zheng's win has not come completely unexpectedly following impressive displays as an unseeded player at the US Open in which she stunned eighth-seeded Iga Swiatek and Madison Keys (22) and then taking eventual champion Elena Rybakina to three sets before the Chinese star bowed out of the calendar's final grand slam.
In the Chinese capital, the home favourite upset Anna Kalinskaya (15), Marie Bouskouva (18), Elina Svitolina (6) and Elise Mertens (13). She now turns her attention to the Wuhan Open in with her campaign starting on Tuesday against American Ann Li.