BackgroundEven though family planning 2020 has made remarkable progress about solving the issue of unmet need for family planning, 70% of women in a developing countries who do not want to conceive are not using it. There are limited research that provided detail information regarding barriers of modern contraceptive utilization during postpartum period in the study area. In addition, previous study also recommended that to conduct using mixed quantitative and qualitative design for further investigations to answer these “why” questions and narrow these gaps.ObjectiveThis study aimed to assess postpartum modern contraceptive utilization and associated factors among postpartum women in Kena woreda, Konso zone, South Ethiopian Regional State, Ethiopia, 2023.MethodsA mixed type community based cross-sectional study design was conducted among 605 women in Kena woreda, from September 1–30/2023 out of 628 sampled mothers. Multistage sampling technique was used to select study participant and data was collected using semi-structured pretested questionnaire and entered in to Epi data version 3.1 and then exported to STATA version 14 for analysis for quantitative. The association between variables was analyzed using bivariate and multivariable binary logistic regression and level of significant determined with adjusted odd ratio at 95% CI and P-value less than < 0.05. After translation and transcription, manual thematic analysis was applied to the qualitative data.ResultsThe prevalence of modern contraceptive use among women during postpartum period in Kena woreda was found to be 39.01% [95% CI: 35.18–42.96%]. Menses resumed (AOR = 1.63; 95% CI: 1.02, 2.59), linked to the family planning unit during their child`s immunization (AOR = 2.17; 95% CI: 1.45, 3.25), family planning counselling during antenatal care visit (AOR = 1.63; 95% CI: 1.10, 2.42) and good knowledge towards modern contraceptive (AOR = 1.53; 95% CI: 1.03, 2.26) were factors associated with postpartum contraceptive utilization. Partner oppose, myths and misconception, need for excess family size, religious prohibition, fear of side effect,menses not resumed, lack of counselling and privacy room, and lack of transportation to health facility were barriers to modern postpartum contraceptive utilization. Conclusions and recommendationsThe utilization of postpartum contraceptives was found to be lower than the target set by the 2020/21 national reproductive health strategy plan, which aimed to increase contraceptive method usage to 50%. Menses resumed, family planning counselling during antenatal care visit, linked to the family planning unit during child immunization and good knowledge were factors associated to modern postpartum contraceptive utilization. Strengthening service integration and family planning counseling during antenatal care visits and encourage mothers to start using modern family planning methods before menses resume are important. Overcoming barriers including partner opposition, myths, religious beliefs, fear of side effects, lack of counseling at health facilities, and transportation challenges is essential.