The effect of light-to-moderate alcohol consumption on cancer risk remains controversial. We examined the association between low-level alcohol consumption and cancer mortality. A cohort study included 331,984 Korean adults free of cancer at baseline who underwent a comprehensive health checkup examination. Participants were categorized into never drinkers, former drinkers, and current drinkers who were further divided into light, moderate, heavy, and very heavy drinkers. Vital status and cancer-related deaths were ascertained through links to national death records. During 1,633,906 person-years of follow-up (median 5.3 years interquartile range 3.8-6.2), 374 cancer-related deaths were identified (cancer-cause mortality rate of 23 per 105 person-years). When former and never drinkers were classified as non-drinkers, the light drinkers had a lowest risk of cancer mortality compared with non-drinkers and other current drinkers (J-shaped); however, with consideration of lifetime abstinence history, current drinking was positively associated with cancer mortality in a dose-dependent manner. When changes in alcohol drinking status and confounders during follow-up were updated as time-varying covariates and never drinkers were used as the reference, the multivariable-adjusted hazard ratios (HRs) (95% confidence intervals, CIs) for cancer mortality among current light, moderate, heavy, and very heavy drinkers were 1.58 (1.03-2.43), 2.28 (1.41-3.70), 2.34 (1.42-3.85), and 2.97 (1.80-4.90), respectively, and the highest risk of cancer mortality was observed in former drinkers, who had an HR (95% CI) of 3.86 (2.38-6.28). Alcohol consumption was significantly and positively associated with an increased risk of cancer mortality in a dose-dependent manner, beginning with light drinkers.