Despite coming through in straight sets, it looked like an upset may be on the cards in the early stages of the contest as Hercog attacked the vulnerable Ivanovic serve to secure a break.
However, Ivanovic responded impressively to dictate the tempo for long spells from the back of the court and she responded with three breaks of her own to wrap up the opener in 37 minutes.
The 27-year-old has reached just one final in 2015, but she quickly grew in confidence to find form on serve and crucially break Hercog in the fourth game of the second set.
Hercog, who knocked out 11th seed Ekaterina Makarova in the second round, kept her hopes alive when Ivanovic's service troubles resurfaced and allowed the Slovenian to break to love.
However, she was unable to capitalise on the opportunity as Ivanovic hit back immediately before holding her nerve to set up a last-eight clash with Belinda Bencic.