Kvitova, who is vying for her second title of the year after winning the St Petersburg Ladies Trophy in February, will take on seventh-seed Buzarnescu, who came back to beat Italy's Camila Giorgi 4-6 6-3 7-5 in the other semi-final.
In a marathon encounter lasting two hours and 25 minutes, Buzarnescu found herself on the back foot for extended periods thanks to Giorgi's raw power but clung before making her superior shot selection count.
She won while receiving, as Giorgi sent her to serve to crash into the net for her eighth double fault of the match.
"I was so happy I was able to win - it's a lot of stress because I have my birthday today," said Buzarnescu, who turned 30. "I never stopped believing."