This study examines the role of income inequality in shaping the aging-inflation nexus using data from 95 emerging and developing economies (EMDEs) over the period 1990–2023. These economies have experienced both rising income inequality and a gradual increase in share of the older population. The results show that population aging exerts a deflationary effect when income inequality is high, and this finding remains robust across multiple specifications. To explain this relationship, we discuss two underlying mechanisms: first, the decline in labor supply associated with aging reduces the natural rate of output and inflation; and second, the growing of political influence of older populations can foster preferences for lower inflation. Our findings contribute to the broader discussion on macroeconomic stability in the context of demographic transition and inequality. Policy implications include raising the retirement age to enhance labor force participation among the elderly, thereby mitigating income inequality and supporting more balanced macroeconomic outcomes.