Background: Cytotoxic drugs (CDs) administration and occupational exposure is a worldwide concern. Inappropriate handling may cause toxic residues to infiltrate hospital environments and patient care areas, and can even be traced to patients' homes. Hence, the study sought to assess knowledge and practices on the safe handling of cytotoxic drugs Among Oncology Nurses at Tertiary Teaching Hospitals in Addis Ababa, Ethiopia. Methods: The researchers conducted a hospital-based cross-sectional study among 77 nurses from April 1-30, 2019. Purposive sampling was used in recruiting the respondents. Structured questionnaires were filled through self-administered interviewing. Data were analyzed using SPSS version 23 software. Multiple linear regression was performed to see the association between dependent variables and independent variables at a p-value of less than 0.05. Results: Mean score of knowledge and practice of nurses was 7.82±2.22 out of 15 and 22.1 ±5.50 out of 40 respectively. Nearly 69% of nurses reported the lack of training program on the handling of CDs at their workplaces and the use of Personal Protective Equipment (PPE) remains suboptimal as none used all of PPE. Nurses who had not heard about CDs had an average knowledge score of 0.33 points lower than nurses who had heard about CDs (p ≤ 0.01). Nurses who have scored higher knowledge points had 0.33 points more practice score of safe CD handling than those who had lower knowledge score (p < 0.05) and also married nurses had average safe CDs handling practice score 0.27 points lower than their counterparts (p < 0.05). Conclusion:Nurses' knowledge and practice of safe handling of cytotoxic drugs are inadequate. Nurses who have scored higher knowledge points and are married were more likely to practice safe CD handling. Provision of proper PPE and training regarding the handling of CDs for Oncology Nurses are recommended and chemotherapy safety protocol and guidelines should be established.