Background: Unmet supportive care needs for cancer patients refer to needs that call assistance or services as an individual perceives are required to achieve the optimal level of physical, psychological, informational, patient care, and sexual well-being. Objective: To assess unmet supportive care needs and associated factors among cancer patients at cancer treatment centers in Northwest Ethiopia public hospitals, 2023. Methods and materials: Institution-based cross-sectional study was conducted from March 20 to April 27, 2023, on cancer patients in Northwest Ethiopia Public hospitals. A systematic random sampling technique was used to select the study participants. Data was collected by using structured interview-administered questionnaires. After the data was checked for its completeness, it was coded and entered in to Epi data version 4.6 and exported into SPSS version 27 for analysis. A binary logistic regression model was used to determine the associated factors. On bivariable regression analysis variables with a p- value <0.2 was entered into a multivariable model for further analysis and p-value <0.05 was confirmed as statistically significant. Result: A total of 410 adult cancer patients took part in this study making a response rate of 96.9% with mean age of 49.5 ± 14.67 years. The overall prevalence of unmet supportive care needs among cancer patients was 98.3%. Psychological, physical, information, patient care, and sexuality domains had 85.1%, 81.5%, 74.6%, 68 %, and 48.3% respectively. Being a farmer, old age, higher and secondary education attainment, testicular cancer, treatment options of radiotherapy and surgery, time since diagnosis <24 months, poor performance status, and weak social support showed statistically significant associations with unmet supportive care needs in different domains. Conclusion and recommendation: This study showed an enormous amount of unmet supportive care needs among cancer patients. Occupation, education, cancer type, social support, treatment option, performance status, age, and time since diagnosis were variables that showed statistically significant associations with unmet supportive care needs of different domains. Hence, the government and health professionals had better work together to advance the needs of cancer patients. Keywords: Cancer, Northwest Ethiopia, supportive care, unmet need