Sixty-three patients with moderate-to-severe symptomatic flat feet were randomized to receive either customized 3D-printed foot orthoses (n=32) or prefabricated foot orthoses (n=31). The primary outcome of interest was pain reduction, assessed via the visual analog scale (VAS). Secondary outcomes included satisfaction with orthosis dimensions, weight, durability, comfort, and effectiveness using a modified QUEST questionnaire. Outcomes were assessed at baseline and after 4 weeks of use. Overall, the results of the study revealed a significant reduction in VAS pain scores in the 3D-printed group (P < 0.001) but not in the prefabricated group. Satisfaction with comfort and effectiveness was also significantly higher in the 3D-printed group. These findings suggest that customized 3D-printed orthoses may be a more effective short-term intervention for reducing pain and improving comfort in patients with flat feet.