Muguruza, who reached the quarter-finals at Roland Garros in the past two years, will next face either Russian 27th seed Ekaterina Makarova or Belgium's unseeded Yanina Wickmayer.
Muguruza, looking to become the first Spanish woman to lift the Suzanne Lenglen Cup since Arantxa Sanchez-Vicario in 1998, broke in the sixth game and wrapped the opening set by winning the last 12 points. She showed no sign of weakness in the second set, allowing her opponent just five points.