The world number 24 had already seen off Elina Svitolina just hours earlier in a rain-delayed quarter final -- Wang's highest-ranked top 10 scalp this year -- despite admitting she had been shaking with nerves ahead of the restarted match.
Wang now faces unheralded Dayana Yastremska in Sunday's final, after the Ukrainian teenager dumped out China's number two Zhang Shuai in the earlier semi-final.
In a see-saw contest strewn with jaw-dropping rallies and breaks of serve, Wang, 26, saved three consecutive set points in the first set tie-break before eventually succumbing 5-7.
She then recovered in dramatic style, coming down from 0-40 down at 5-4 to clinch the second set.
Down 0-3 in the third set, Wang admitted she was thinking of going home before a pep talk from her coach stiffened her resolve.
"I had nothing to lose against her -- she's a very good player," Wang said.
"I just tried to be more patient and if I had a chance then to go for it." She then clawed her way back from a 1-4 deficit, with Muguruza --appearing exhausted and out of ideas by the end of the match -- losing her final service game with two unforced errors.
The sixth seed sealed the titanic win with an ace.
A disconsolate Muguruza paid tribute to her opponent.
"I think she played very well especially in the important moments, she came back in the third set playing incredible tennis," the Spanish world number 13 and fourth seed said.
- 'Nervous from the first ball' -
The ex-Wimbledon and French Open champion still has two more tournaments to play this season, which she said she was happy with despite her Grand Slam highlight being a semi-final finish at Roland Garros.
Wang had earlier needed just 10 minutes to wrap up her victory against world number five and top tournament seed Svitolina, again sealing the 6-2, 6-4 win with an ace.
The 26-year-old Chinese was serving for the match at 5-2 in the second set when the heavens opened Friday evening.
Svitolina is still in the running for one of the three remaining places at the WTA Finals in Singapore later this month and she now faces an anxious wait to see if a quarter-final finish will be enough to secure qualification.
She said she knew little about the 102-ranked Yastremska, who powered to a 7-5, 6-4 victory over Zhang to reach her first WTA Tour final.
The 18-year-old -- who earlier this year became the first player born this millennium to break into the top 100 -- appeared overwhelmed after the win, lying on her back in Centre Court to soak up the cheers of the crowd.
"I was nervous from the first ball," Yastremska said.
"After match point I fell on the floor because I felt so relaxed, that was my instinct to go and lie because I needed to put it away, the emotions.
"I even started to cry a little bit.
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