Abstract Background In China, less than one third of infants under 6 months of age are being exclusively breastfed. Maternal rural-to-urban migration contributes to these low rates of breastfeeding practices. Therefore, the aim of this study was to assess the prevalence of breastfeeding practices and associated factors among rural-to-urban migrant children and local children with infants aged 0–12 months in China, 2018. Methods Data were collected from a population-based cross-sectional survey in 2018 that included 6995 infants from eight urban areas (four metropolis and four medium sized/small cities) in China. The prevalence of breastfeeding practices was calculated using a 24-h recall questionnaire for all infants aged under 12 months. Logistic regression was conducted to examine the association between the prevalence of breastfeeding practices and maternal migrant status, after adjusting for sociodemographic characteristics, mother-infant health information and supportive information. For exclusive breastfeeding, we further analyzed its association with maternal rural-to-urban migration, stratified by maternal education level, maternal resident place and maternal ethnicity, respectively. Results The overall prevalence of ever breastfeeding, exclusive breastfeeding, predominant breastfeeding and age-appropriate breastfeeding (exclusive breastfeeding of infants under 6 months of age and complementary feeding from six to 12 months of age) was 97.51, 29.84, 59.89 and 45.07%, respectively. Rural-to-urban migrant children were less likely to be exclusively breastfed compared to local children (AOR 0.81, 95% CI 0.68, 0.95). Stratified by different sociodemographic variables, a negative association between exclusive breastfeeding and rural-to-urban migration was only found in the group with high education level, in the group living in metropolis and in the group of minorities, respectively. Conclusions The overall prevalence of breastfeeding practices was low in both rural-to-urban migrant children and local children. Besides common strategies, special approaches should be provided for urban highly educated migrants.