Cutaneous malignant melanoma is a rare but fatal disease in East Asia. Despite its increasing incidence, a general lack of awareness about the disease was noted. This study aims to provide population-based prognostic analysis of melanoma with sentinel lymph node biopsy (SLNB) in Taiwan. We conducted this retrospective cohort study using the data from Taiwan National Health Insurance Research Database during 1997–2013. The study cohort contains 3284 patients. The 5-year survival rates of patients undergoing SLNB and not undergoing SLNB were 45.5% and 33.6%. In multivariate analysis, age ≥ 80 years [adjusted hazard ratio (aHR) = 2.15] and male (aHR = 1.19) were associated with a poorer prognosis, while high social economic status (SES) (aHR = 0.69) and undergoing SLNB (aHR = 0.84) were good prognostic factors. Old age and low SES were associated with lower percentages of patients undergoing SLNB (P < 0.001). E-value analysis suggested robustness to unmeasured confounding. In conclusion, undergoing SLNB was associated with a better prognosis. The poor prognosis of old age and low SES may be due to decreased percentages of patients undergoing SLNB. Therefore, we recommend that SLNB should be performed on patients, especially in old age or low SES, who are candidates for SLNB according to current guidelines to achieve maximal survival.