Rising global temperatures and the urban heat island effect can amplify heat-related health risks to urban res-idents. Cities are considering various heat adaptation actions to improve public health, enhance social equity, and cope with future conditions beyond past experience. We present the City-Heat Equity Adaptation Tool (City -HEAT), which suggests optimal investments for mitigating urban heat and reducing health impacts through modifications of built (cool roofs/pavements) and natural (urban afforestation) environments and reductions of people's heat exposure (cooling centers). The optimization considers multiple public health and social objectives under a wide range of future scenarios. An application to Baltimore, MD (USA) demonstrates how City-HEAT can generate Pareto-efficient multi-year heat adaptation plans. We quantify effectiveness-efficiency-equity tradeoffs among alternative plans and show the advantages of flexible decision-making. City-HEAT can be adapted to the natural, built, and social environments of other cities to support their urban heat adaptation planning, recog-nizing local objectives and uncertainty.