To achieve a national energy access target of 90% urban and 51% rural by 2035, combat climate change, and diversify the energy sector in the country, the Zambian government is planning to integrate other renewable energy resources (RESs) such as wind, solar, biomass, and geothermal into the existing hydro generation-based power system. However, to achieve such targets, it is essential for the government to identify suitable combination of the RESs (electricity generation fuel mix) that can provide the greatest sustainability benefit to the country. In this paper, a multicriteria decision-making framework based on analytic hierarchy process and system dynamics techniques is proposed to evaluate and identify the best electricity generation fuel mix for Zambia. The renewable energy generation technologies considered include wind, solar photovoltaic, biomass, and hydropower. The criteria used are categorized as technical, economic, environmental, social, and political. The proposed approach was applied to rank the electricity generation fuel mix based on nine sustainability aspects: land use, CO2 emissions, job creation, policy promotion affordability, subsidy cost, air pollution reduction, RES electricity production, RES cumulative capacity, and RES initial capital cost. The results indicate that based on availability of RESs and sustainability aspects, in overall, the best future electricity generation mix option for Zambia is scenario with higher hydropower (40%) penetration, wind (30%), solar (20%), and lower biomass (10%) penetration in the overall electricity generation fuel mix, which is mainly due to environmental issues and availability of primary energy resources. The results further indicate that solar ranks first in most of the scenarios even after the penetration weights of RES are adjusted in the sensitivity analysis. The wind was ranked second in most of the scenarios followed by hydropower and last was biomass. These developed electricity generation fuel mix pathways would enable the country meeting the future electricity generation needs target at minimized environmental and social impacts by 2035. Therefore, this study is essential to assist in policy and decision making including planning at strategic level for sustainable energy diversification.