Using indicator-based assessment, this study examines the energy security of nine Association of Southeast Asian Nations (ASEAN) member countries to see how it has evolved over the past 12 years and identifies a country-specific energy security context for each country. The assessment uses 42 energy security indicators, which can be separated into five components: overall energy balance, socio-economic aspect, domestic energy resources, overseas energy demands and resources, and diversification of energy supply. The findings show different energy security situations among ASEAN member nations that are a result of national energy contexts, specifically uneven economic and energy infrastructure developments. The context, at a national level, affects the connotation of energy security and the interpretation of the indicators, which reflects different primary issues of concern regarding energy security. At the international level, due to the diversity, the interconnection of intra-regional energy markets could contribute to energy self-reliance of the region. Adversely, the difference could hinder the prospect of cooperation due to the lack of consensus on shared value.