Mladenovic was no match for Svitolina, who steamrolled the No.7 seed in a brutal 6-1 6-0 victory at the WTA 250 tournament on Friday (AEST).
Ukrainian star Svitolina reeled off the last 11 games to set up a semi-final clash with Rebecca Peterson.
Peterson moved through 7-6 (7-4) 2-6 4-1 after Tereza Martincova retired hurt.
Alize Cornet, the No.9 seed from France, rallied past No.5 seed Marketa Vondrousova 2-6 6-4 6-3, while No.8 seed Marta Kostyuk won the first set 7-6 (7-4) but trailed Varvara Gracheva 5-3 in the second before the match was suspended because of bad light.
At Tennis in the Land, No.1 seed Daria Kasatkina was upstaged by Magda Linette 6-1 6-2 in the quarter-finals.
No.2 seed Anett Kontaveit survived 6-3 5-7 7-2 against Katerina Siniakova in Cleveland, while fellow seed Sara Sorribes Tormo also won through to set up a semi-final clash.