Background: Female genital mutilation (FGM) is non-therapeutic surgical modification of the female genitalia. It has received growing attention from government and organization to eliminate. Despite of efforts, it is a widely practiced and remains a serious problem for large proportion of women. While, the contributing factors FGM may vary from one ethnic group/culture to another culture; data are limited regarding the knowledge attitude and practice of FGM and predictors in the study area. Objective: To assess knowledge attitude and practice of FGM and associated factors among women reproductive age group in Loka Abaya woreda southern Ethiopia, 2018 G.C. Methods: A community based cross-sectional quantitative study design complemented with qualitative study was conducted in January, 2018. For quantitative study, a total of 796 reproductive age group women were selected, and for qualitative study, three focus group discussions and three in-depth interviews were conducted using unstructured guideline. Multi stage sampling technique was used. For the survey, structured and pre-tested questionnaire was used. The collected data were analyzed by SPSS for windows version 22.0. Both bivariate and multivariable logistic regression analysis were used to determine the effect of factors on the outcome variables and to control for potential confounding. Odds ratio with 95% confidence interval was used to identify factors associated with female genital mutilation. Result: Totally 752 women participated in the survey; 472(62.6%), and 460(61.2%) and women reported to have good knowledge and favorable attitude toward FGM, respectively, and 522(69.4%) had undergone FGM. Factors significantly associated with knowledge, were education, marital status, religion Muslim and economic status. Factors heard message against practice, residence, believe continuation of practice, religion and economic status were significantly associated with attitude. Age of respondents 25-35 year, occupation, residence education and believe continuation of practice were had significant association with practice. Reasons why they practice were to respect culture, to avoid shame, and to avoid stigma. Conclusion: In this study area good knowledge and favorable attitude was 62.6% and 61.2% respectively. However, practice (69.4%) was high demanding appropriate intervention and follow up