Halep erased a 1-5 deficit and saved three set points in the second set as the Romanian star triumphed 6-4 7-5.
Seeded second for the WTA Premier Mandatory tournament, Halep was leapfrogged by Naomi Osaka atop the rankings after the Australian Open in January.
However, Halep is now just one win away from moving back to the top of the WTA summit following her one hour, 37-minute victory against 18th seed Wang midweek.
"I just found out from my coach that I need one more match to be No.1 again," Halep said. "I think it's pretty much in my head, and I'm happy that I'm in this position again.
"It gives me confidence, because from the two months of the off-season, I didn't believe I would be so close again so fast. So it's going to be a big challenge, but I like to play with the pressure. So I hope tomorrow I play my best."
Standing in the way of Halep and her bid to retake the top ranking is fifth seed Karolina Pliskova, who defeated teenager and compatriot Marketa Vondrousova.
Pliskova was too good for the 19 year-old, winning 6-3 6-4 to reach her third semi-final of the season after overcoming a 0-3 deficit in the second set.