Alcohol use remains a persistent occupational hazard among military populations, yet research on its predictors within West African armed forces has lagged behind the operational demands soldiers face. This study examined combat exposure and military service duration as predictors of alcohol use among Nigerian infantry soldiers, and tested whether service duration moderates the relationship between combat exposure and alcohol use. A cross-sectional survey was administered to 292 active-duty infantry personnel (92.8% male; Mage = 32.27, SD = 7.87) at Jaji Military Cantonment, Kaduna State, using the Combat Exposure Scale and the Alcohol Use Disorders Identification Test (AUDIT). Hierarchical regression showed that combat exposure (β = .76, p < .001) and military service duration (β = .22, p = .028) each independently and significantly predicted alcohol use, together with covariates accounting for 59% of the variance. However, PROCESS Model 1 moderation analysis, supported by Johnson–Neyman follow-up, indicated that service duration did not significantly moderate the combat exposure–alcohol use relationship (p = .064); combat exposure remained a significant predictor across the full range of service duration observed. Findings suggest combat exposure and service duration function as independent, additive risk factors rather than interacting ones, with implications for exposure-triggered rather than tenure-based alcohol screening in military settings.