Despite the increasing number of older people, many with cognitive impairment (CI), in hospitals, there is yet to be an evaluation of hospital-wide interventions improving the management of those with CI. In hospitalized patients with CI, there are likely to be associations between increased complications that impact on outcomes, length of stay, and costs. This prospective study will evaluate the effectiveness of an established hospital CI support program on patient outcomes, patient quality of life, staff awareness of CI, and carer satisfaction. Using a stepped-wedge, continuous-recruitment method, the pre-intervention patient data will provide the control data for usual hospital care. The intervention, the Dementia Care in Hospitals Program, provides hospital-wide CI awareness and support education, and screening for all patients aged 65+, along with a bedside alert, the Cognitive Impairment Identifier. The primary outcome is a reduction in hospital-acquired complications: urinary tract infections, pressure injuries, pneumonia and delirium. Secondary outcome measures include cost effectiveness, patient quality of life, carer satisfaction, staff awareness of CI, and staff perceived impact of care. This large-sample study across four sites offers an opportunity for research evaluation of health service functioning at a whole-of-hospital level, which is important for sustainable change in hospital practice.