Objectives: This study examines the impact of evaluation criteria—relevance, coherence, and effectiveness—on the success of humanitarian projects in the Gaza Strip, with efficiency as a mediating factor. It aims to provide a comprehensive understanding of how these criteria interact to enhance project outcomes in complex humanitarian settings. Methods/Analysis: The research employs Structural Equation Modelling (SEM) to analyze data collected from 350 respondents involved in humanitarian projects. The analysis assesses the direct and mediated effects of relevance, coherence, and effectiveness on project success, offering empirical insights into the role of efficiency in optimizing resource utilization. Findings: The results indicate that relevance, coherence, and effectiveness significantly influence project success, while efficiency strengthens these relationships by ensuring better resource allocation and implementation. The study highlights the importance of community engagement, alignment with local needs, and cultural sensitivity in achieving sustainable project outcomes. Novelty/Improvement: This research presents an integrated evaluation framework that enhances understanding of the interplay between key project assessment criteria and efficiency in humanitarian work. The findings provide actionable insights for organizations operating in complex environments like Gaza, helping refine project planning and execution strategies to improve sustainability and impact.