Purpose Despite growing attention to innovative work behavior (IWB) in demanding work contexts, little is known about voice as a mechanism through which job characteristics relate to IWB. To address this gap, this paper incorporates organizational role theory (ORT) and conservation of resources (COR) theory to examine how, in the healthcare context, job characteristics such as role clarity (i.e. lack of understanding of work expectation) and role overload (i.e. insufficient time to complete work tasks) affect IWB via employee voicing. Design/methodology/approach Data were collected from 424 healthcare employees within one of Italy’s largest private hospital groups. The study employed structural equation modeling to examine relationships between role clarity, role overload, employee voice behavior and IWB. A moderated mediation model was applied to assess both the direct and indirect effects of job characteristics on IWB through employee voicing, while also exploring the moderating impact of role overload on these relationships. Findings The findings indicate that both role overload and role clarity relate positively to employee voice behavior, which in turn affects IWB. Further, role overload attenuates both the direct relationship between role clarity and employee voicing and the indirect relationship between role clarity on IWB via employee voicing. This highlights role overload’s dual influence as both a stimulant and a constraint on innovation-related behaviors. Originality/value This study presents two key novel contributions. First, it advances our understanding of how different job characteristics interact to influence IWB by identifying employee voice as a key mediator. Second, it offers new theoretical insights into the IWB debate by integrating ORT and COR theories, establishing a novel and fertile foundation for exploring the determinants of IWB. To the best of our knowledge, this is among the first studies (if any) to emphasize the importance of role characteristics for IWB in high-pressure contexts such as the healthcare sector.