This study contributes to a growing literature body of studies aimed at explaining socio-economic-related health inequality in non-communicable diseases (NCDs), with a focus on older people who are commonly affected by socio-economic gradient in later life. It identifies factors associated with self-reported NCDs and examines socio-economic-related health inequality in self-reported NCDs between rural and urban Vietnamese older people. This cross-sectional study utilised data from the Viet Nam Ageing Survey. A sample of 2,682 older people aged 60 and over (urban = 703, rural = 1,979) was analysed. Concentration indices were computed to measure socio-economic inequalities in self-reported NCDs. Concentration index decomposition analysis was performed to determine the relative contributions of the determinants to explaining those inequalities. Significant socio-economic inequalities in self-reported NCDs favouring the rich were found, in which the degree of inequality was more pronounced in urban areas than in their rural counterparts. Household wealth and social health insurance were the main drivers contributing to increased socio-economic inequalities in self-reported NCDs in urban and rural areas, respectively. Among disadvantaged groups, older people living alone, with lowest wealth and with social health insurance had highest probability of reporting at least one NCD for both areas. Public policies aimed at narrowing wealth gaps and expanding and improving principle roles of social health insurance should prioritise the most disadvantaged groups in order to achieve health equality.