After a highly competitive start to the final, the 20-year-old raced to a 6-4 6-0 victory with seven straight games.
The feat was particularly impressed given this was only Muguruza's second tournament following a six-month lay-off after ankle surgery.
"I didn't expect to win a lot of matches in the second tournament of the year, but I knew that I'd just worked so hard before," said Muguruza, who plays 24th seed Kaia Kanepi in the first round of the Australian Open.
"When I was at home I was thinking to myself, 'If I go to the tournament I'm going to fight so much,' and that's what I did. I was like a big bull out there."