Abstract: This study evaluates the impact of feasibility studies on the success of the Busanza Housing Estate slum upgrading project in Rwanda, focusing on economic, social-cultural, and environmental dimensions. Using a mixed-methods approach, data were collected from 109 participants, including stakeholders, residents, and officials, via surveys, interviews, and document analysis. Descriptive and inferential methods, such as Z-scores and regression analysis, were used to analyze the data. Results show that economic feasibility significantly contributed to financial sustainability, job creation, and investment (mean = 3.78). Social-cultural feasibility helped reduce inequality and encouraged community involvement, leading to strong local support (mean = 3.80). Environmental feasibility proved vital in addressing climate risks and promoting sustainability (mean = 3.77). Strong correlations were found between all three feasibility dimensions and project success. The study recommends incorporating comprehensive feasibility studies in future slum upgrading initiatives for inclusive, sustainable urban development. These findings offer practical guidance for project management and urban planning in Rwanda and similar contexts.