While concerns about online gambling behavior exist, the involved psychological mechanisms and playing patterns across digital media and locations remain unclear. This study provides information from a nationally representative sample of 1841 adult Belgian respondents. Theoretically, the study contributes by introducing the concept of habit strength as a predictor of gambling behavior. Habit strength is viewed as complementary to gambling predictors that are derived from the Theory of Planned Behavior. Structural equation modeling indicates that both habit strength and perceived friend/family gambling behavior (norms) were associated with online gambling intent, which in turn contributed to an increase in problem gambling. Moreover, habit strength predicted problem gambling both directly and indirectly via intent to play online or spend over 20 Euro. Results further show that online gambling is quite prevalent, but that gambling applications differ in their digital and physical location pattern. For example, sports betting is often done via mobile devices. This study shows that complementary concepts from communications research (habit) and public health (theory of planned behavior) can be used to successfully predict gambling behavior. The relationship between online gambling and problem gambling indicates a need for policy makers and researchers to consider harm reduction in this new online environment.