Breastmilk substitute (BMS) companies are targeting mothers using aggressive and unethical marketing strategies that violate the WHO Code in both urban and rural areas in China, this study reveals. Tactics varied in different locations; for instance, mothers in small and medium cities and non-poor rural counties were more likely to receive free BMS samples during pregnancy, while the mothers in urban areas were more likely to receive advice to feed babies with BMS from health facilities. Results demonstrate an urgent need to strengthen enforcement of Code regulations throughout the country, especially within health facilities and digital and mass media.