The global outbreak of coronavirus disease 2019 (COVID-19) and the resulting lockdown measures have raised concerns regarding their effect on alcohol consumption. We investigated alcohol use during lockdown in a population of college students, usually characterized by social and heavy drinking. We also tested the predictive role of pre-lockdown drinking motives on alcohol consumption during lockdown. We collected data from 1951 French-speaking Belgian students during the lockdown period (April 1st – May 3rd, 2020) through a cross-sectional online survey. Participants self-reported their daily alcohol consumption (1) during a typical week in normal circumstances (i.e., before lockdown), and (2) since lockdown onset. We also assessed drinking motives and severity of alcohol use before lockdown. Our findings showed that 68.2% of the sample reported a lower alcohol consumption during lockdown compared to before lockdown, 17.2% conversely reporting a higher consumption. Enhancement, social and coping motives were all associated with heavy drinking before lockdown. Enhancement and social motives predicted lower alcohol consumption during lockdown among heavy drinkers. Conversely, coping motives, as well as social motives among low drinkers, predicted higher consumption during lockdown. Conformity motives, as well as enhancement motives among low and moderate drinkers, did not predict alcohol consumption before or during lockdown. Overall, several pre-lockdown drinking motives reliably predicted alcohol consumption during lockdown and could thus be used to identify at-risk populations and to tailor intervention programs on alcohol misuse during sanitary crises.