Background: Surgical patients are high risk of malnutrition due to extensive catabolic reactions and increased nutrient requirement after surgery. Although nutritional care is the focus of peri-operative nursing care, it is poorly practiced in most of the health facilities. Objective: The aim of this study was to assess knowledge, attitude, practice, and associated factors of nurses on the nutrition of surgical patients in Referral Hospitals of Bahir Dar city, Ethiopia. Methods: An institution based cross-sectional study was conducted. A total of 422 nurses were selected by trained data collectors using simple random sampling and a pre-tested self-administration questionnaire. Data entered into Epi-info & exported to SPSS. Bivariate and multivariable logistic regression analyses were used to identify factors. A p-value of < 0.05 was used to determine a significant association with odds ratio at 95% CI. Result: In this study, 410 of 422 nurses were participated with a response rate of 97% that 54.6% were females, and mean age of 29 years. About 56%, 37%, and 35% of the nurses had positive attitude good knowledge & practice on the nutrition of surgical patients, respectively. Being male (AOR=2.13, 95%CI, 1.3, 3.44), using internet (AOR=2.09, 95%CI, 1.23, 3.54) working in FHCSH (AOR=.28, 95%CI, .16, .50), knowledge sharing with peers (AOR=2.04, 95%CI, 1.22, 3.40 were significant factors of nurses’ knowledge. Similarly, being male (AOR=2.23, 95%CI, 1.39, 3.59), age <30(AOR=2.82, 95%CI 1.75, 4.54), and having poor knowledge (AOR=.34, 95%CI, .21, .57) were significant factors associated with nurses’ attitude. Being female (AOR=2.69, 95% CI,1.62,4.44) reading nutrition books(AOR=2.59, 95% CI, 1.52,4.39) physician order (AOR=1.82 95% CI, 1.11, 3.00), experience sharing with peers (AOR=1.74, 95%CI 1.05, 2.87) nurse to patient ratio<1:5 (AOR=1.75,95%CI, 1.01,3.02) having poor knowledge (AOR=.50, 95%CI, .30,.83), and having negative attitude(AOR=.51 95%CI, .30, .84 were significantly associated with nurses’ practice. Conclusion: Although the attitude of nurses towards surgical patients’ nutrition was relatively higher, their knowledge and practice levels were poor. Sex, working place, and access to nutritional information sources were factors associated with the KAP of nurses. Therefore; improving nutritional information sources in terms of training, books, internet, experience sharing, etc. is crucial to increase the KAP of nurses on surgical patients’ nutrition.