The experience sampling method (ESM) is a structured diary method with high ecological validity, in that it accurately captures the everyday context of individuals through repeated measurements in naturalistic environments. Our main objective was to investigate the feasibility of using ESM in individuals with acquired brain injury (ABI). A second goal was to explore the usability of ESM data on a clinical level, by illustrating the interactions between person, environment, and affect. The PsyMate device provided ABI patients (N = 17) with ten signals (beeps) per day during six consecutive days. Each beep was followed by a digital questionnaire assessing mood, location, activities, social context, and physical well-being. Results demonstrated high feasibility with a 71% response rate and a 99% completion rate of the questionnaires. There were no dropouts and the method was experienced as user-friendly. Time-lagged multilevel analysis showed that higher levels of physical activity and fatigue predicted higher levels of negative affect at the same point in time, but not at later time points. This study illustrates the potential of ESM to identify complex person–environment dynamics after ABI, while generating understandable and easy to use graphical feedback.