Small power systems subject to hazards in the island cities of Southeast Asia increase the vulnerability of energy security, and require good climate-risk management, data integration and adaptive energy planning. This study proposes and validates a model that connects climate-risk salience to island energy security through renewable-energy planning capability, and investigates the institutional coordination as a moderating variable. We examined four constructs with 22 seven-point items with a cross-sectional survey online with 428 respondents from a range of utility, regulatory, municipal, developer, finance, research and community stakeholders across seven island contexts in the region. Ordinary least squares estimation with 5000 bootstrap resamples, mediation, moderation and ten-fold predictive assessment were used to estimate a component-based structural model. Energy security is negatively predicted by climate-risk salience (β = −0.142) while planning capability is positively predicted (β = 0.487). Island energy security is strongly associated with planning capability (β = 0.557) which mediates the relationship between climate-risk salience and energy security (β = 0.271). Greater institutional coordination strengthens the association between planning capability and energy security (β = 0.172). The model accounts for 54.5% of security variance, indicating that risk awareness is effective when applied in coordinated adaptive planning.