Background <p>Work-related hand eczema (WRHE) is a common occupational disease in Europe, associated with impaired quality of life and a substantial socioeconomic burden. As skin protection behaviour critically influences disease course, mobile health interventions may help establish and maintain routines. The smartphone app ‘<i>Mein Hautschutz im Alltag</i>’ (MiA; German for ‘<i>My Skin Protection in Everyday Life</i>’) was developed to support patients with WRHE, but its clinical effectiveness has not yet been evaluated.</p> Methods <p>This quasi-randomised controlled trial will enrol 286 adults with WRHE attending a 3-week inpatient programme at a specialised dermatology clinic. Participants are allocated in clusters based on admission date to either care as usual (control) or care as usual plus an individual goal-setting interview and a 6-month access to the MiA app (intervention). The primary outcome is change in skin protection behaviour from baseline to 6 months post-discharge. Secondary outcomes include clinical and self-rated skin condition, action control, and quality of life. Analyses will follow the intention-to-treat principle using linear mixed models.</p> Discussion <p>This is the first systematic evaluation of the MiA app’s effectiveness in patients with WRHE in a quasi-randomised controlled trial. By combining a structured goal-setting interview with the MiA app, the intervention aims to support the long-term adoption and maintenance of protective behaviours in both occupational and private settings. Key limitations include the quasi-random allocation by admission date (no true randomisation), lack of allocation concealment and blinding, reliance on self-reported primary outcomes, and a 6-month follow-up. Despite these constraints, the pragmatic design aims to generate decision-relevant, real-world evidence for WRHE care.</p> Trial registration <p>German Clinical Trial Registry DRKS00036627. Registered on April 14, 2025.</p>