Background: Postnatal care service is preventive care, practices and assessments that are designed to identify and manage complications for both the mother and the newborn within the first six weeks of birth. A clear understanding of factors associated with complete PNC services utilization is important to help in the development and the implementation of evidence-based approaches to increase utilization of PNC services. The aim of the study was to identify the Prevalence of complete postnatal care utilizations and associated factors among women gave birth in the last 12 months in Ezha district, southern Ethiopia. Methods: A community based cross-sectional study was conducted in Ezha district. A two stage sampling technique was applied. A total of 568 mothers from ten selected kebeles were included in the study by using computer generated random numbers. Data were collected using pretested semi-structured questionnaire through face to face interview and entered to EpiData3.1 and exported to SPPS version 23. Principal component analysis (PCA) was performed to assess wealth status of the participants. Bivariate and Multivariable logistic regression analysis were performed in order to identify the factors significantly associated with Complete post natal care utilization at the level of significance of p value <0.25 with 95% CI of COR and <0.05 with 95% CI of AOR respectively. Results: The prevalence of complete post natal care utilization in the study area was 19.6%. The factors; maternal education of secondary and above [AOR: 4.3; 95%CI: (2.15, 8.05)], having antenatal visits [AOR:3.75; 95%CI:(1.78, 7.92)], Caesarean delivery [AOR:3.96; 95%CI: (1.5,7.94)], having good knowledge on PNC [AOR: 5.31; 95%CI:(2.34,10.05)] and being model house hold [AOR:3.61; 95%CI: (1.97,6.64)] were identified as independent factors for complete postnatal care utilization in multivariable logistic regression analysis. Conclusion: Complete postnatal care service utilization in the study area was low. Strengthening information education and communication on the importance of complying with recommended postnatal care, work on model house hold creation, and increasing number of antenatal care visits are the necessary measures that should be done by concerned bodies to enhance complete postnatal care utilization in the district. Keywords: Postnatal care, complete postnatal care, utilization, district, associated factors.