Technology-assisted supplemental work (TASW) has become a common demand in flexible work arrangements. Building on the effort–recovery model, we investigated how two TASW events after work (i. e., continuing work tasks, being contacted) affect psychological detachment and relaxation in the evening and, in turn, emotional exhaustion the next morning. With an event-oriented approach, we analyzed daily diary data of 215 employees (686 daily observations over five consecutive workdays). The results of multilevel path analysis showed a negative direct effect (a) of both TASW events on psychological detachment and (b) of being contacted on relaxation. A similar pattern was found for the indirect effects on exhaustion. The direct relationships between TASW events and emotional exhaustion were not significant. We conclude that employees should avoid TASW whenever possible in order to sufficiently recover from work and begin their next workday refreshed.