Dementia is a significant cause of death in the older population and is becoming an important public health issue as the population ages and the prevalence of dementia increases. The Braden score is one of the most commonly used clinical tools to assess the risk of skin pressure injury in patients, and some studies have reported that it may reflect the state of frailty of patients. The present study attempted to explore the association between Braden score and 90-day mortality, pressure injury, and aspiration pneumonia in older patients with dementia in the intensive care unit (ICU). The study involved extracting crucial data from the Medical Information Market for Intensive Care IV (MIMIC-IV) database using Structured Query Language, with a license certificate obtained after completing the necessary training and examination available on the MIMIC-IV website. A retrospective analysis was performed on older patients with dementia, aged 65 or older, who were first admitted to the ICU. Ninth and tenth revision International Classification of Diseases codes were used to identify patients with dementia. The primary outcome was 90-day mortality. Cox proportional hazards models were used to determine the association between Braden score and death, and hazard ratios (HR) and 95% confidence intervals (CI) were calculated. Propensity score matching and E-value assessments were employed for sensitivity analysis. A total of 2892 patients with a median age of approximately 85years (interquartile range 78.74-89.59) were included, of whom 1625 were female (56.2%). Patients had a median Braden score of 14 (interquartile range 12-15) at ICU admission. Braden score at ICU admission was inversely associated with 90-day mortality risk after adjustment for demographics, severity of illness, treatment and medications, delirium, and sepsis (adjusted HR: 0.92, 95% CI: 0.87-0.98, p=0.006). Patients were divided into two groups with a cut-off value of 15: high-risk group and low-risk group. Compared to the low-risk group (Braden score >15), the risk of 90-day mortality was significantly increased in the high-risk group (Braden score ≤15) (adjusted HR: 1.52, 95% CI: 1.10-2.09, p=0.011, E-value: 2.01), the risk of pressure injury (adjusted OR: 2.62, 95% CI: 2.02-3.43, E-value: 2.62) and aspiration pneumonia (adjusted OR: 2.55, 95% CI: 1.84-3.61, E-value: 2.57) was also significantly higher. The Braden score may be a quick and simple screening tool to identify the risk of adverse outcomes in critically ill older adults with dementia.