Background: Research on the use of psychotropic drugs in people with alcohol-related neurocognitive disorders is virtually nonexistent. We examined the prevalence of antipsychotic drug use and its effect on mortality among patients with Wernicke–Korsakoff syndrome (WKS) or alcohol-related dementia (ARD). Methods: In this nationwide register study, we collected data on the medication use and mortality of all persons aged ≥40 diagnosed with WKS (n = 1149) or ARD (n = 2432) between 1998 and 2015 in Finland. We calculated the prevalence of antipsychotic use within one year of diagnosis and the adjusted cumulative mortality of antipsychotic users versus non-users in relation to the age-, sex-, and calendar year-matched general population. Results: Of the WKS and ARD patients, 35.9% and 38.5%, respectively, purchased one or more antipsychotic drugs in the year following diagnosis. The adjusted cumulative mortality of the antipsychotic users was significantly lower than that of non-users in both the WKS and ARD groups, where the adjusted hazard ratios (95% CI) were 0.85 (0.72–0.99) and 0.73 (0.65–0.81), respectively. WKS and ARD patients using antipsychotics were less likely to die of alcohol-related causes than antipsychotic non-users, but the difference was significant only in the ARD group. Conclusions: This population-based study shows that antipsychotic use is common in patients with WKS or ARD. In contrast to other dementia studies, our results indicate that the mortality of antipsychotic users is significantly lower than that of non-users. The lower mortality could be explained by decreased alcohol use and better healthcare coverage in antipsychotic users.