Diabetes mellitus is a chronic metabolic disease that can cause peripheral neuropathy, resulting in decreased foot sensitivity and an increased risk of diabetic foot ulcers. One non-pharmacological intervention to improve foot sensitivity is diabetic foot exercise using a tennis ball. This study aimed to determine the effect of diabetic foot exercise using a tennis ball on foot sensitivity among patients with diabetes mellitus in the working area of UPTD Puskesmas IV South Denpasar. This study employed a pre-experimental design with a one-group pretest-posttest approach. A total of 26 respondents were selected using a total sampling technique. Foot sensitivity was assessed using the 10-g Semmes-Weinstein Monofilament (SWM). Data were analyzed using the Wilcoxon Signed Rank Test because the Shapiro-Wilk normality test indicated that the data were not normally distributed. The results showed that the mean foot sensitivity score increased from 7.46 ± 1.749 before the intervention to 8.65 ± 0.892 after the intervention. The Wilcoxon Signed Rank Test showed a p-value < 0.001 (p < 0.05), indicating a statistically significant effect of diabetic foot exercise using a tennis ball on improving foot sensitivity. Diabetic foot exercise using a tennis ball can be considered a simple, safe, and effective non-pharmacological nursing intervention to improve foot sensitivity and help prevent diabetic foot complications.