Passion can drive entrepreneurs to new heights of success and fulfilment, but the dark side can also lead to conflict with relationships and activities. Work addiction goes a step further as it demands the entrepreneur’s time and energy even when they are off the clock. This study explores the relationship between entrepreneurial passion and work addiction, leaning on the Dualistic Model of Passion. It also investigates the possibility that personality traits influence this connection. Empirical evidence suggests that obsessively passionate entrepreneurs are more likely to encounter work addiction than their less passionate counterparts. The data also supports a weak link between harmonious entrepreneurial passion and work addiction, with harmoniously passionate entrepreneurs being less susceptible to work addiction. Finally, there was minimal support for the idea that the Dark Triad traits (narcissism, Machiavellianism, psychopathy) play a role in this exchange. There is a secondary nuance to this study regarding passion and addiction. It provides evidence that passion with one target can relate to addiction with another. This encourages the examination of other cross-target passion and addiction relationships.