"It's never easy to play Simona," said Jabeur, who lost to Halep in Dubai earlier this year. "Really happy with the fact that I took my revenge. I can see that I'm progressing in my game and in other stuff. I hope I can continue with this level to play the other matches."
The 21st-ranked Halep had 20 unforced errors and only eight winners.
Elsewhere in the women's draw, 12th-seeded American Jessica Pegula defeated home-crowd favorite Sara Sorribes Tormo 6-4, 6-2 to set up a semifinal against with Jil Teichmann, who beat Ukrainian Anhelina Kalinina 6-3, 6-4.
The Associated Press contributed to this report.