Populations are ageing at varying rates of development. Countries with developed economies have experienced such changes to their population structures. Examinations have been conducted with regard to how respective societies can accommodate the said changes in their health and social systems, but this research mostly focuses on more developed regions rather than lower-income countries. This paper discussed the experience of ageing populations in developing economies, which comprise the majority of the global older population. They display a vastly different experience from high-income countries, especially when viewed within the level of world regions. The cases presented here were from Southeast Asian countries in order to have a wide range of examples in terms of differences in country-income categories. In lower and middle-income countries, there are older adults who: continue working as their primary income source, are non-members of pension systems, and provide intergenerational support rather than only receiving it. The COVID-19 pandemic situation was also included here, as policies were reformed to address current needs that highlighted the challenging situation of older adults. The populations of countries that have yet to age substantially, especially those in the least-developed regions, can utilise this paper’s recommendations in order to prepare for changes in the age structures of their societies.