Background: Achieving sustainable practice changes to ensure best-practice nursing care in acute hospital environments can be challenging and is not well understood. A multi-faceted practice change intervention was implemented in a large Australian hospital to enhance the capacity of the nursing workforce to provide quality care for older patients with cognitive impairment (CI). Methods: Thirty-four experienced Registered Nurses (RNs) became Cognition Champions (CogChamps), and led practice-change initiatives to improve nursing care for older patients (≥65 years) on six wards in one hospital. The CogChamps received comprehensive education about dementia and the identification, prevention, and management of delirium. Over five months, they were supported to develop and implement ward-specific Action Plans designed to change care practices. Nurse-patient interactions were observed and patient charts were audited prior to the implementation of the plans and regularly throughout, using a purpose built Audit/ Observational tool. Data were also collected at a comparable hospital where there were no CogChamps. Data were analyzed for evidence of practice change. Results: Observational and audit data were collected for 181 patients (average age = 82.5 years) across the two hospitals. All patients had CI and both cohorts had similar behavioral characteristics requiring a high level of care assistance [e.g. 38% displayed evidence of confusion/disorientation and a majority experienced meal-time difficulty (62-70%)]. While nursing practices were generally the same at both hospitals, some differences were evident (e.g. analgesia use was higher at the control hospital). Following implementation of Action Plans, significant increases in nurses' assessments of patients' cognitive functioning (35 to 69%), and administration of analgesia (27 to 48%) were observed at the intervention hospital, although only the improvement in cognitive assessments was maintained at three months follow-up. No other changes in nursing processes were evident. Conclusion: The CogChamps project demonstrates how RN champions were empowered to educate their colleagues about dementia and delirium resulting in a sustained increase in cognitive assessments by ward nurses. Practice improvements were mostly associated with clearly defined Action Plan tasks and goals and where responsibility for task completion was clearly assigned. These elements appear to be important when implementing practice changes. Trial registration: Australian Clinical Trials Registration Number: ACTRN 12617000563369. Retrospectively registered.