Aims: The Internet is the leading medium among European adolescents in contemporary times even more time is spent on the Internet than watching television. This study investigates associations between online alcohol marketing exposure and onset of drinking and binge drinking among adolescents in four European countries.Method: A total of 9038 students with a mean age of 14.05 (SD 0.82) participated in a school-based survey in Germany, Italy, the Netherlands and Poland. Logistic regression analyses of cross-sectional cross-country survey data were undertaken. Exposure to online alcohol marketing, televised alcohol advertising and ownership of alcohol-branded items was estimated to be controlled for relevant confounders. Onset of drinking and binge drinking in the past 30 days were included in the study as outcome variables.Results: Adjusted for relevant confounders, higher exposure to (online) alcohol marketing exposure was found to be related to the odds of starting to drink (p < 0.001) and the odds of binge drinking in the past 30 days (p < 0.001). This effect was found to be consistent in all four countries. Active engagement with online alcohol marketing was found to interact more strongly with drinking outcomes than passive exposure to online alcohol marketing.Conclusions: Youngsters in the four European countries report frequent exposure to online alcohol marketing. The association between this exposure and adolescents' drinking was robust and seems consistent across national contexts.