Waste generation has increased dramatically in urban settings, especially in developing countries. In Kisumu, approximately 400 tons of waste are generated daily and discarded haphazardly at open, uncontrolled, and overflowing dumpsites. The substantial risks associated with such an inefficient solid waste management (SWM) system are overly concerning. Various researchers have recommended plausible measures for sustainable waste management, including the disposal of waste in landfills, however; to date, no study has employed a robust methodology for selecting potential landfill sites in Kisumu. This study sought to utilize GIS and MCDA for optimal landfill siting. A hierarchical scheme was formed, that included social, economic, and environmental factors geared toward protecting the health of the public, reducing the cost of waste management, and minimizing environmental impacts. A total of 11 criteria were evaluated in a subjective decision-making process. The analytical hierarchy process (AHP), a technique of MCDA, was used to assign weights to each criterion based on their relative importance. All the weighted layers were overlayed using GIS to determine ideal landfill sites. The final output map was a contiguous representation of highly suitable to less suitable landfill areas. A customized graphical user interface toolbox that models the landfill siting process was developed, for use primarily in auditing the sites.