Breastfeeding mothers often face challenges with insufficient breast milk supply for their baby's nutritional needs. Purple sweet potato leaves contain galactagogues, which can increase breast milk production. Objective: to determine the effectiveness of flavonoids in purple sweet potato leaf biscuits on prolactin levels and breast milk production in breastfeeding mothers. Methods: this was a true experimental study with a pretest/posttest control group design, consisting of two groups: all breastfeeding mothers in the East Purwokerto Community Health Center (Puskesmas) working area, with a sample size of 20 respondents per group. The intervention group was given biscuits containing 1 gram of purple sweet potato leaf extract and the control group was given education on breastfeeding mothers for 14 days. Body weight was measured using a scale, bowel and urinary frequency using a questionnaire, and prolactin levels using an ELISA kit. Bivariate analysis used Wilcoxon and Man-Whitney. Results: The average infant weight after intervention in the intervention group was 2983.50 g, the control group was 2911.40 g (p=0.010), the average number of bowel movements after intervention in the intervention group was 2.60 times, the control group was 2.25 times (p=0.461), the average number of urinations after intervention in the intervention group was 6.90 times, the control group was 6.20 times (p=0.040), the average prolactin hormone level after intervention in the intervention group was 265.15 ng/ml, the control group was 195.90 ng/ml (p=0.008). Conclusion: Giving purple sweet potato leaf biscuits is effective in increasing prolactin hormone levels and breast milk production in breastfeeding mothers.