Background <p>Nurses who care for patients with trauma exposure, psychological distress, substance use issues, or other vulnerable conditions typically work in demanding clinical environments. Based on conservation of resources theory, this study examined the association between nurses’ perceived trauma-informed climate and voice behavior for nursing care improvement with psychological empowerment as a mediating mechanism and cultural humility as a boundary condition.</p> Methods <p>A three-wave questionnaire survey with two-week intervals was conducted among registered nurses from six hospitals and related healthcare institutions in Guangdong and Shanxi Provinces, China. A total of 508 matched responses were included. We conducted confirmatory factor analysis and path analysis using Mplus 8.0.</p> Results <p>Trauma-informed climate was positively associated with voice behavior and psychological empowerment. Psychological empowerment was positively associated with voice behavior and partially mediated the relationship between trauma-informed climate and voice behavior. Cultural humility positively moderated the relationship between trauma-informed climate and psychological empowerment. The indirect association between trauma-informed climate and voice behavior through psychological empowerment was stronger at higher levels of cultural humility.</p> Conclusions <p>Nurses’ perceived trauma-informed climate was linked to voice behavior for nursing care improvement partly through psychological empowerment, and this indirect association was stronger when cultural humility was high. These findings should be interpreted as associations rather than causal effects. The results highlight the relevance of trauma-informed work conditions, empowerment-related cognitions, and cultural humility in understanding nurses’ constructive voice in complex nursing environments.</p> Clinical trial registration <p>Not applicable, as this study was a questionnaire-based survey and did not involve a clinical trial.</p>