Although the need for sustainability of waste disposal sites (WDS) is largely agreed upon by various stakeholders, there is still a limitation in evaluating sites' sustainability. This study aimed to define ecological sustainability for WDS and develop a framework for its assessment. A WDS's ecological sustainability was defined as the site's capacity to take up waste without compromising the surrounding ecosystems' health and their abilities to self-regenerate or provide other ecosystem services. A model, called EcoSWaD, was developed in this study to assess the ecological sustainability of WDS. The model has 35 indicators divided into five major themes: (i) location suitability; (ii) operational sustainability; (iii) environmental sustainability; (iv) socioeconomic sustainability; and (v) site capacity sustainability. The EcoSWaD brought together all the different interpretations and indicators in the diverse fields of sustainability study or practice to facilitate a comprehensive and meaningful WDS assessment. Testing the model at the Kiteezi landfill showed that the location, environmental, socioeconomic and site capacity themes at the landfill had low values: 18.7, 19.1, 16.9 and 15, respectively. The operation theme had a very low value of 13.5, showing that the landfill's biggest sustainability concerns stem from site operation and the resultant impact on the environment, local community and site capacity. The overall Sustainability Score of 83.1 showed that the landfill's sustainability is low. A tool for the application of the EcoSWaD can be found at https://ecoswad.org/app/console/.