The third-ranked Romanian was back on court for the first time since a shoulder injury forced her out of the Miami Open last month, and it was only her second match since her straight-sets loss to Serena Williams in the Australian Open quarterfinals in February.
There was no sign of rust as Halep wrapped up her win over Vondrousova in less than an hour without facing a single break point. Halep will play Ekaterina Alexandrova in the quarterfinals after the Russian upset eighth-seeded Belinda Bencic 6-1, 7-5.
Elina Svitolina came through a tougher test as she beat three-time Grand Slam champion Angelique Kerber 7-6 (4), 6-3. Svitolina was 3-1 down in the tiebreaker before winning six of the next seven points, and she didn't face a break point in the second set. The fourth-seeded Ukrainian will face Petra Kvitova in the quarters.