The construction of "zero-waste cities" aims to reduce solid waste generation at the source and enhance its resource utilization rate to promote sustainable urban development. To rigorously assess the impact of the "zero-waste city" pilot policy on medical waste generation, this study employs the synthetic control method based on dynamic panel data from 35 large and medium-sized Chinese cities between 2013 and 2022. The treatment group includes Beijing, Tianjin, Shenzhen, and Chongqing—four cities selected in the first batch of the pilot program—while the remaining cities serve as the control group. Results indicate that only Beijing achieved a statistically significant reduction in per capita medical waste generation, averaging 9.22 tons less per 10,000 people annually compared to its synthetic counterpart, representing an 18.7% decrease. This outcome may be attributed to targeted financial support, the establishment of a closed-loop, full-process supervision system, and extensive social mobilization. These findings suggest that other cities can draw valuable lessons from Beijing's experience to advance their own "zero-waste city" initiatives.