Background: Birth registration is one of the most important events in a child’s life. Commitment of government, legislative framework of a country and absence of infrastructure that can support the logistical aspects of birth registration, the value that individuals and families give to birth registration, and lack of adequate knowledge of how to register a child are the bottlenecks associated with birth registration. Therefore, the aim of this study was to assess the birth registration and associated factors among children less than 12 months in South Mecha wereda and delivers valuable information about the problem which helps the concerned body to take an intervention on identified gap. Objective: To assess birth registration and associated factors among children less than 12 months South Mecha Wereda, West Gojjam Zone, Amhara Region, Ethiopia, 2022 Methods: A community based cross sectional study design was conducted. On a total of 805 children less than 12 months were included. Multistage sampling techniques were employed. Children were selected by systematic random sampling technique. The collected data cleaned, coded and entered into EPI INFO and then exported to SPSS version 26. Binary and multivariable logistic regressions were performed to see the association of each of the independent variables with the outcome variable. Result: A total of 794 (98.6%) children were participated in this study. From the total 11.96% (95%CI=7.01,15.97)children were registered. Able to read and write caregiver(AOR=1.71, 95%CI=1.23, 4.91), primary complete caregiver(AOR=2.02, 95%CI=1.30,5.73), urban residents(AOR=2.09,95%CI=1.88, 3.51), being exposed to television(AOR=4.71, 95%CI=3.10, 9.349), ANC follow up(AOR=1.86,95%CI=1.38, 4.89), PNC visit(AOR=7.81, 95%CI=6.04, 14.94), health center delivery(AOR=3.58, 95%CI=3.11, 8.81), hospital delivery(AOR=5.14, 95%CI=1.31, 9.73) and good knowledge(AOR=9.5,95%CI=8.64,19.22) were significant association with birth registration. Conclusion and Recommendations: Birth registration in the study area is lower compared to other studies. Urban resident, caregiver education status, being exposed to television, institution delivery, ANC, PNC and good knowledge follow up were identified as associated factor with birth registration practice. To improve birth registration practice the organizations working at local level should increasing institutional delivery, improving PNC and ANC uptake. Keyword: Birth registration, Less than 12 month’s children, South Mecha, West Gojjam