The 23-year-old held her nerve amid rain delays and tie-breaks to set up a showdown with either Angelique Kerber or Sabine Lisicki and move closer to a top-10 ranking.
The unseeded Mladenovic had accounted for three seeds on her way to the semi-final but crashed out at the penultimate hurdle in a match that lasted two hours 20 minutes including an hour of rain delays.
Pliskova said afterwards:??”I was shaking. She (Mladenovic) played better in the second set than the first set, and a third set would have been very tough.
“The end of the match was key. I was trying to stay calm and to centre on every point and to hold serve. My last return was a bit lucky.”
The Czech will now play in her??fourth final of the year.