People with gambling problems gamble despite resolutions to stop. These choices may be more likely in contexts that allow for them to be justified (e.g., after a productive day at work), termed the licensing effect. This has not been tested in the domain of gambling. Using a daily diary design across 21 days (n participants = 156, n reports = 2,516), gamblers trying to reduce their gambling reported their daily justification opportunities (e.g., feelings of effort and achievement) and whether they gambled, as well as daily aspects of self-control (i.e., craving, conflict, suppression) and affect (positive and negative). Gambling occurred on 33% of the reported days. Prior-day justification opportunities were associated with a higher likelihood of gambling. Prior-day suppression showed a similar effect, whereas prior-day negative affect showed the opposite effect. After gambling, people experienced stronger cravings, weaker suppression, and poorer well-being (lower positive affect and higher negative affect). Our findings show that people may use justifications to gamble, despite its negative consequences, indicating that the licensing effect may, in part, explain why people gamble despite resolutions to stop.