ObjectivesLow birth weight is one of the global agendas that have an impact on the short and long-term health status. A cross-sectional study from March 1 to April 1, 2018 was conducted. 381 mother–newborn pairs were participated. This study aimed to assess the prevalence and associated factors of low birth weight in the Northwest part of Ethiopia.ResultsThe prevalence of low birth weight was 14.9% (95% CI 11.7–18.9). Being preterm [adjusted odds ratio (AOR) = 4.1; 95% CI 1.7–9.9], absence of ante-natal care follow-up (AOR = 3.4; 95% CI 1.2–9.5), malaria attack during pregnancy (AOR = 4.2; 95% CI 1.6–11.1), anemia during pregnancy (AOR = 2.6; 95% CI 1.03–7.0), and lack of iron supplementation (AOR = 4.0; 95% CI 1.3–12.6) were predisposing factors to low birth weight. On the other hand, infants born from employed mothers (AOR = 0.1; 95% CI 0.01–0.92) were less likely to born with below normal birth weight. The prevalence of low birth was high as compared to WHO estimation.