This study aimed to determine and assess the factors influencing job performance among the National Irrigation Administration (NIA) Region IV-A (CALABARZON) employees. A total of sixty (60) employees from the different Field Offices of NIA Region IV-A (CALABARZON) were surveyed using a self-determined questionnaire. By analyzing various variables, the researcher aims to identify the critical areas for intervention and enhancement. The study entails determining the factors that influence the employees job performance, such as work motivation, satisfaction, organizational culture, leadership style, and physical work environment. The study used a mixed method using qualitative and quantitative approaches and statistical tools such as mean, standard deviation, One-way ANOVA and Pearsons correlation coefficient to analyze the data gathered. Based on the results, the relationship between the demographic profile of the respondents and the level of performance of the employees of NIA Region IV-A has no significant effect on job performance. On the other hand, the results on the relationship of the influential factors of work motivation, work satisfaction, leadership style, organizational culture, and physical work environment significantly affect the employees work quality, work productivity, and managerial efficiency, which implies job performance. Thus, it is recommended that the National Irrigation Administration (NIA) Region IV-A (CALABRZON) review and assess the factors that affect the employees job performance. The influential factors such as the incentives, the workload distribution, the physical environment, and the organizational culture may delve deeper into the possible enhancement of the interventions for employees to be more motivated and satisfied in the organization and produce a better work output and job performance. This study provides valuable insights for NIA Region IV-A (CALABARZON) in intensifying their employees job performance through the development of the influential factors that impact job performance.