2018 Porsche Tennis Grand Prix – Singles

Laura Siegemund was the defending champion, but lost in the second round to CoCo Vandeweghe.

Karolína Plíšková won the title, defeating Vandeweghe in the final, 7–6, 6–4.

15-year-old Marta Kostyuk became the youngest player to win a main draw match in Stuttgart since Martina Hingis in October 1994.