The economy of Kazakhstan is locked into reliance on fossil fuel energy sources. Its government is seeking to diversify and deliver sustainable development. We develop an approach to decision-making to support critical decisions over the necessary $67 billion in electricity investments to 2050 that can simultaneously contribute to a sustainable economy. We apply structured decision-making and cost-benefit analysis, align politically by incorporating the collective expertise of an interdisciplinary group of stakeholders to identify Policy Options, commercial assumptions and externalities, and fill data gaps using technical, economic and environmental data from global sources. Our approach quantifies net present value of these identified Policy Options, explores sensitivities, and suggests alternative investment pathway. Our results indicate policymakers should switch from coal and focus on harnessing the commercial and economic advantages of gas and hydropower for electricity generation. These options would be cheaper and have considerably lower emissions and water usage than the current production mix.