Nine days after knocking the Czech out of the Eastbourne International in the second round, Boulter repeated the feat on Centre Court at Wimbledon, with a 3-6, 7-6(4), 6-4 win over the 2021 finalist.
Swiatek, the freshly crowned French Open champion, will look to extend her 35-match winning streak when she takes on qualifier Jana Fett after Friday's draw at the All England Club.
Poland's Iga Swiatek expanded her lead at the top of the WTA rankings released on Monday after her French Open triumph in Paris over American Coco Gauff.