Corporate Social Responsibility is a complicated aspect of decision-making for most corporates. There is no ideal model and clear evidence that one method is more effective than others are. Some corporates prefer to do it in house while others, due to complexity or other reasons, outsource. That divergence necessitated the current study. The study aimed to identify the determinants of outsourcing Corporate Social Responsibility (CSR) in Kenya. The study had the following research objectives: To explore the factors that influences the decision to outsource CSR functions, to determine the effects of outsourcing CSR functions on organizational performance and, finally, to establish the impact of outsourcing CSR on stakeholders’ engagement. The researcher adopted a descriptive research design. Purposeful sampling aided the selection of organizations from the various sectors identified for the purpose of this study. The study utilized both primary and secondary with the former adopting structured questions that had open and closed ended questions. Statistical Package for Social Sciences (SPSS) was used in analyzing the data and the study results presented in tables, figures, graphs, and charts. The study established existence of a positive relationship and of statistically significant difference between group factors that influence the decision to outsource CSR functions. The study findings showed statistically significant relationship and statistically insignificant difference between the groups with regards to the effects of outsourcing CSR functions on organizational performance. The same result was evident on the impact of outsourcing CSR on stakeholders’ engagement where there was absence of statistically significant relationship. In the case of factors influencing outsourcing CSR functions, the study noted that there is statistically significant difference between the groups. The study established a relationship between outsourcing CSR functions and organizational performance. The study concluded that cost, optimal resource utilization, competency, and knowledge are main factors influencing the decision to outsource. The study further deduced that cost-based, resource-based, and knowledge-based factors as well as organizational factors are pivotal in outsourcing CSR functions.