See main article: article and 2021 Koser Jewelers Tennis Challenge.
Madison Brengle was the defending champion, having won the previous edition in 2019,[1] but lost in the second round to Lesley Pattinama Kerkhove.
Nuria Párrizas Díaz won the title, defeating Greet Minnen in the final, 7–6(8–6), 4–6, 7–6(9–7).