Physical child punishment is a critical public health problem that exhibits negative and long-lasting mental and physical health consequences. Yet, the predictors of physical punishment are understudied in developing countries, and disparities that exist between levels of economic status are not known well. The socioeconomic predictors of physical child punishment were investigated using three rounds of the Multiple Indicator Cluster Survey (MICS) results in a lower middle-income country, Viet Nam from 2006 to 2014. A total of 16,784 households that have answered the child punishment questionnaire from MICS data from 2006 to 2014 were included in the analysis. Descriptive statistics, univariate, and multivariate logistic regression analyses were conducted. A secular trend of disparity was investigated with and without the parents' normative values on physical punishment. Children in Viet Nam have been subject to some form of violent physical punishment by their parents or caregivers. About half of the children in the poorest households (44.7%) experienced physical child punishment while lesser percentage of children in the richer households experienced physical child punishment. Disparities existed across different wealth groups as the prevalence of physical child punishment decreased: the gap between the poorest and the richest group widened. Compared to the richest households, the poorest households were more likely to experience physical child punishment AOR 1.58 (95% CI 1.39-1.79). There is a decrease in the prevalence of physical punishment over the recent years in Viet Nam, socioeconomic disparities, in contrast, have increased, and the poorest children have a higher risk of experiencing physical child punishment. Such disparities should be considered in future research and intervention development.