Venturing into business is thought to play an important role particularly to retirees as a source of extra income and also for keeping themselves busy in retirement. However, in spite of efforts from various stakeholders to enhance success of the retirees’ businesses, they have been performing poorly. According to the Retirement Benefits Authority (RBA) most businesses started by retirees fail within the first three years. The main objective of the study was to examine the factors affecting the performance of businesses of public corporation retirees in Kisumu. The study used a sample size of 193 retirees, who were picked from a population of 642 through stratified sampling technique. The study was a descriptive survey of the retirees and used both primary and secondary data. Primary data was collected from relevant retirees using structured questionnaires. Secondary data was obtained from the institutional reports and records of the retirees. The data collected was analyzed using descriptive statistics and presented in form of tables and frequency distributions. This study revealed that the major factors affecting performance of retirees’ businesses include financial stability, physical and mental strength, entrepreneurial skills and family base, which accounted for significant failure of businesses of retirees of public corporations in Kisumu. It was also revealed that many retirees lacked proper human relations skills to motivate and retain internal customers (employees) as well as maintain consistently satisfied customers. The study recommended that retirees in business should endeavour to attend trainings/seminars to improve their business and financial management skills. Further, the study recommended the enactment of a compulsory preretirement training on financial and business management for employees with at least five years to retirement. The researcher suggested that a similar study be done focusing on external factors affecting business performance and also focus on retirees in the private sector.