: Adolescent women face a high risk of unintended pregnancies and consequent unsafe abortions, with devastating consequences to their health. Establishing adolescents’ knowledge about unsafe abortion is imperative to developing an adolescent-focused strategy for addressing the menace. Methods: This study was conducted to determine the knowledge and perceived factors contributing to unsafe abortion among female adolescents in Enugu South Local Government Area. A cross-sectional descriptive survey was used among a sample of 362 respondents picked randomly from four secondary schools. A structured questionnaire was used for data collection and data analysis was done using SPSS version 24. Result: Findings revealed that most of the respondents (98.9%) were Christians. The majority (94.1%) have heard about unsafe abortion, with their parents (40.1%) being the most frequent sources of information, fellow students or friends (24%). Stigmatization (94.3%) was the most reported socioeconomic factors that affect unsafe abortion, fear of expulsion from school (91.9%), fear of rejection by parent/family (91.6%), and fear of rejection by the would-be husband (72.8%). Poor availability of health-care services (82%), high cost of safe abortion services (71.9%), stigmatization against adolescents (67.7%), lack of health insurance coverage for safe abortion services (67.7%), and negative attitude of health workers (76.3%) were the strongest identified healthcare-related factors promoting unsafe abortion among adolescents. Conclusion: It was recommended that continuous and intensive health education and re-orientation of the adolescents on the problems of unsafe abortion and scaling up sex education in schools to enlighten the students on the dangers of immoral sex, unwanted pregnancy, and unsafe abortion.