The US Open finalist from Russia plays Alexander Zverev of Germany or Italy's Matteo Berrettini in Sunday's decider as the next generation takes centre stage in China.
The 23-year-old Medvedev, who has lifted three titles in a breakthrough 2019, beat Greece's Tsitsipas 7-6 (7/5), 7-5.
Medvedev has now seen off the 21-year-old — who defeated world number one Novak Djokovic on Friday — in all five of their matches.
There was nothing in it as they entered the first-set tie break after 43 minutes of high-quality tennis.
Seventh-ranked Tsitsipas blinked first, gifting set point when he shanked a forehand and then doing the same moments later to put the fourth-ranked Russian a set up.
Medvedev broke the Greek — who repeatedly tried to gee up the crowd — in the third game of the second set.
The Russian served for the match at 5-4, only for Tsitsipas to dig in and break for 5-5, before Medvedev did likewise.
Tsitsipas smacked the ball out the court in a rage, before Medvedev sealed match in the 12th game of the second set.
The 22-year-old Zverev — who ousted Roger Federer on Friday — and Berrettini, 23, play their semi-final later Saturday.
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