The Danish world number five secured a 6-0 6-1 victory inside an hour, saving both of the break points she faced.
[STORY: Rory McIlroy split was like someone dying, says Caroline Wozniacki]
Seventh seed Agnieszka Radwanska, the 2012 champion, also progressed with 6-4 7-5 win over Anna Schmiedlova.
"I was in trouble, especially in that second set," said Radwanska. "But what was most important is that I was really playing good shots in the really key points, in the break points.
"I'm very glad that I could finish in two sets," she said.
Elsewhere, Russia's Ekaterina Makarova beat Karin Knapp 6-1 6-3 and Germany's Andrea Petkovic ousted Christina McHale in a 6-2 6-2 win.
Results from the Miami Women's Singles Round 2 matches on Thursday
26-Elina Svitolina (Ukraine) beat Bojana Jovanovski (Serbia) 6-3 7-6(3)
8-Ekaterina Makarova (Russia) beat Karin Knapp (Italy) 6-1 6-3
4-Caroline Wozniacki (Denmark) beat Madison Brengle (U.S.) 6-0 6-1
22-Alize Cornet (France) beat Elena Vesnina (Russia) 6-4 6-1
Kaia Kanepi (Estonia) beat 28-Varvara Lepchenko (U.S.) 6-2 6-4
Kristina Mladenovic (France) beat 19-Barbora Zahlavova Strycova (Czech Republic) 7-5 6-2
9-Andrea Petkovic (Germany) beat Christina Mchale (U.S.) 6-2 6-2
14-Karolina Pliskova (Czech Republic) beat Annika Beck (Germany) 2-6 6-3 6-4
12-Carla Suarez Navarro (Spain) beat Stefanie Voegele (Switzerland) 6-3 6-1
31-Irina Begu (Romania) beat Tereza Smitkova (Czech Republic) 5-7 6-4 6-4
7-Agnieszka Radwanska (Poland) beat Anna Karolina Schmiedlova (Slovakia) 6-4 7-5
Paula Badosa (Spain) beat Zheng Saisai (China) 6-1 7-5
see more at: https://uk.eurosport.yahoo.com/news/tennis-caroline-wozniacki-sails-third-round-miami-211514900--ten.html