The Polish world number two, who was number one for 75 straight weeks, beat home player Mai Hontama, ranked 148 in the world, 6-4,7-5 in the second round after being sidelined in the first round, a so-called bye.
Switatek took a break after the early exit at the U.S. Open and stood over the major tournament in Guadalajara, Mexico, to recover.
In the first set, Hontama had two fights up and 4-1 and in the second the Japanese picked up a disadvantage of 1-5 to 5-5.
First time Swiatek played in Japan
"When I won five straight games in the first set, I showed that I could play my game," Swiatek told the WTA website.
It was the first time Swiatek played in Japan and she can breathe a sigh of relief after moving on.
"It wasn't easy and I'm happy that I was able to solve the problems and move on in the tournament," says Swiatek, who after one match has already reached the quarterfinals where she will face Russian Veronika Kudermetova.