This daily diary study investigates the effects of daily smartphone use for work during off-work hours on work-life conflict. Drawing on role theory which supports the notion that segmentation is a boundary management strategy, the moderating effect of individual’s segmentation preference is proposed. Results of multilevel regression analyses showed that smartphone use for work was positively related to work-life conflict. The result also shows that the preference to integrate work and personal life rather than separate these domains strengthened the relation between smartphone use for work and work-life conflict. The results of this study may help human resource practitioners to better understand the impact of staying connected to work during off-work hours.