Abstract: Background: A client’s satisfaction with expanded program immunization services has good effects on her health and ensures the utilization of services. In developing countries, approximately 8 million children die before they reach their fifth birth day. When compared with a child in Western Europe, an Ethiopian child is 30 times more likely to die by his or her fifth-year birth. Objective: To assess client satisfaction with expanded programs on immunization services and associated factors in Doyogena Woreda, southern Ethiopia, 2021. Methods: A facility-based cross-sectional study design was employed from April 12 to May 31/2021. The total sample size was 402. A simple random sampling technique was used to select health facilities, and a systematic random sampling technique was used to select clients. The data were entered by using Epi data Version 3.1 and analyzed by SPSS version 24 software. Frequency, tables and figures were used. Multi colinearity was checked and the goodness of fit test was done using Hosmer-Lemeshow model goodness fit test. Bivariable analysis was done and variables with p value less than 0.025 were entered to multivariable logistic regression analysis. Statistical significance was declared at p value less than 0.05 with 95% confidence interval. Result: The magnitude of clients’ satisfaction with expanded programs on immunization services was 47.2% [95% CI: 42.0-52.2]. Clients in the age group of 20-24 were 3.2 times more satisfied with expanded programs on immunization services than clients in age groups greater than 35 years [AOR: 3.20, 95%CI: 1.11, 9.27], clients travelling less than thirty minutes to reach the health facility were 9.4 times more satisfied with expanded programs on immunization services than clients who travelled more than thirty minutes [AOR: 9.42, 95%CI: 4.79, 18.53] and clients who were informed on the dose of the vaccination were 2.3 times more satisfied with expanded programs on immunization services than clients who were not informed on the dose of the vaccination [AOR: 2.32, 95%CI: 1.29, 4.17]. Conclusion: Nearly half of the clients were satisfied towards an expanded immunization service program. More efforts are needed to improve services with respect to health workers’ relationships, communication, waiting time for immunization and provision of health information to enhance satisfaction among clients towards expanded programs on immunization services.