Workforce Diversity is a common feature in organizations all over the world. Whereas workforce diversity benefits are easier to list, the best practices in managing these diversities and their contribution to an organization’s performance are less obvious. This paper aimed in examining the effect of workforce diversity management on humanitarian organization performance with a focus on the Kenya Red Cross Society. The study examined how demographic diversity, professional diversity, and cultural diversity affected the organization's performance of the Kenya Red Cross Society. The research was grounded on Social Identity Theory, Self-Categorization Theory, and, Information and Decision-Making Theory. The study adopted a descriptive survey method and correlational design to establish the relationship between workforce diversity aspects and organizational performance within the Kenya Red Cross Society. The target population was the staff of Kenya Red Cross Society, with a bias on Program Coordinators, County Coordinators and Project Officer, and beneficiaries of Kenya Red Cross program activities. The sample frame for the study was 101 personnel members working with the Kenya Red Cross Society as of April 2020. Simple random sampling criteria was employed to collect data on beneficiary satisfaction based on the convenience and availability of beneficiaries across three major programs. Descriptive statistics were computed to explore the general perception of the beneficiaries in terms of their satisfaction with program implementation by the Kenya Red Cross Society and staff on the implementation of their aforementioned diversity management practices. 80% of the staff indicated that KRCS emphasizes candidates’ skills in its recruitments. 71.7% of the staff were aware that KRCS had a policy for equal opportunities regardless of gender differences. However, 34.1% of the respondents were not sure whether the organization has enhanced cultural integration through a culturally diverse recruitment policy. The reliability index coefficient was as per the Cronbach Alpha statistic was 0.824. The study utilized a network of complex structural relationships through variance-based structural equation modelling to build a relationship between dependent and independent variables. The model explained 69.6% of the variability in organizational performance. The results indicated that professional diversity, demographic diversity and, cultural diversity have a significant effect on organizational performance. Demographic diversity management had an indirect effect while professional & cultural showed a direct effect on organizational performance. The study was limited in scope and depth and