Although unhealthy snacking may have detrimental consequences for employee health and organizational outcomes, the role of working conditions on snacking still remains poorly understood. Drawing from optimal arousal theory, we propose and test a conceptual model that explains how under-stimulating conditions of job monotony increase unhealthy snacking behaviors during work due to experienced boredom. Given that individual differences play an important role for eating behaviors, we further propose that trait mindfulness may moderate the relationship between daily work-related boredom and unhealthy snacking, as it can decrease impulsive reactions to boredom. Results from diary data across two workweeks (N = 105) confirmed the positive effect of daily job monotony on unhealthy snacking through work-related boredom. Supplementary analyses revealed that these results persisted above and beyond over-stimulating work stressors (daily workload) and alternative mediators (daily negative affect). Surprisingly, the protective nature of trait mindfulness was not confirmed by our results. The implications of our findings are discussed for theory and practice.