BACKGROUND: Gender-based violence (GBV) is a common human right violence in conflict-affected communities. Women with GBV are prone to experience mental health problems such as post-traumatic stress disorder, depression, and anxiety. However, there is a paucity of evidence as to what extent the problem is affecting internally displaced women (IDW) in Ethiopia. This study aimed to assess the prevalence of GBV and its associated factors among IDW in Northwest Ethiopia. METHODS: A cross-sectional study was conducted among IDW residing at three humanitarian sites from May to June 2022 in Northwest Ethiopia. Study participants were selected using a stratified simple random sampling technique from the three sites. GBV was assessed using a 6-item Assessment Screen to Identify Survivors Toolkit questionnaire for Gender-based violence (ASIST-GBV). Data were analyzed using binary logistic regression. All variables with a p-value of ≤ 0.05 in the multivariable analysis were defined to have a statistically significant association with GBV at a 95% confidence interval (CI). RESULTS: Of 424 approached candidates, 412 (97.2%) of them participated in the study. A one-year prevalence of GBV was 37.9% (95%CI = 33.2-42.6) among IDW in Northwest Ethiopia. The mean age of the participants was 31.3 (± 7.6) years. Young women, 18-24 years old (AOR = 3.52, 95%CI = 2.15-5.34, p ≤ 0.001) and 25-29 years old (AOR = 2.41, 95%CI = 1.57-3.24, p ≤ 0.001) had a statistically significant association with GBV. Moreover, having no social protection (AOR = 3.18, 95%CI = 2.65-6.22, p ≤ 0.001), being current alcohol user (AOR = 2.54, 95%CI = 1.22-4.78, p ≤ 0.001) and being single in marital status (AOR = 1.69, 95%CI = 1.18-2.87, p < 0.01) showed a statistical association with GBV. CONCLUSION: We found a high prevalence of GBV among IDW in Northwest Ethiopia which indicates that IDW are prone to GBV. We call for immediate action and special attention to young women in conflict-affected parts of Ethiopia. It is crucial to establish a system that ensures the safety, security, and well-being of women in humanitarian settings.