Background: Safe clinical practice for patients hospitalised in mental health care during a suicidal crisis is situated within a dynamic, non-linear and uncertain context. Under such complex conditions, the adaptive capacity is considered vital to handling challenges and changes in clinical care. This study aimed to explore safe clinical practice for suicidal patients hospitalised in mental health wards through understanding healthcare professionals' (HCPs') capacities to adapt to challenges and changes in clinical care. Methods: This study applied a qualitative design with focus group and individual interviews. Twenty-five HCPs participated in the focus groups, and 18 participated in individual interviews. The study was conducted in open and locked wards in a university hospital in Norway providing specialised mental health services for patients with mental illness. Results: HCPs described their adaptive capacities for clinical practice relative to three themes. 1) HCPs used expertise to make sense of suicidal behaviour to support complex decision making. Their strategies included setting aside forms and checklists to prioritise trust and making judgements based on more than just patients' spoken words. They improved their understanding by seeking others' perspectives through collaborative sense-making processes involving the healthcare team and patient. 2) HCPs individualised the therapeutic milieu to address the diversity of patients with suicidal behaviour by creating individual clinical pathways, making trade-offs between under-and over-protection and adjusting observations. 3) HCPs described managing uncertainty as necessary for providing safe clinical practice. They managed uncertainty as a team by developing mutual collegial trust and support and creating a shared understanding. Conclusion: HCPs' adaptive capacities are vital to the complex set of practices involved in safe clinical practice for patients hospitalised during a suicidal crisis. By using expertise, individualising the therapeutic milieu, and managing uncertainty, HCPs individually and collectively develop their capacities to adapt to challenges and changes in clinical care. HCPs cannot easily ensure safe clinical practice by following standards; safe clinical practice depends on HCPs' adaptations. Ward systems that ensure collegial trust and support, as well as arenas that foster shared understanding and situational awareness, are needed.