Even though entrepreneurial work is stressful, health promotion interventions are seldom targeted at entrepreneurs, and we know little about how to reach and recruit this hard-to-reach group to such studies. We described and evaluated the recruitment process of a mobile health application intervention study aimed at enhancing work ability and recovery. Finnish microentrepreneurs (N = 1243) were registered for the intervention. We analyzed surveys, interviews, and registration data. Most participants registered through email invitations. The registered microentrepreneurs were not representative of all Finnish microentrepreneurs; females and highly educated individuals were overrepresented, and those working in agriculture were underrepresented. Differences be- tween registration routes were observed: females registered more often through the self-enrollment route, whereas males and older entrepreneurs registered more often through email invitations. The findings indicate that recruitment strategies are associated with participant characteristics. To increase participation rates, persuasive recruitment approaches are needed.