Among the deleterious effects caused by hospitalization of elderly patients in intensive care unit (ICU), delirium and impaired performance in occupations are frequent and have long-term negative outcomes. Delirium protocols described in the literature vary in frequency, intensity, and content regarding pertinent interventions. Occupational Therapy (OT) practices are heterogeneous and generally consist of non-personalized interventions. For this reason, the primary outcome of this research is to evaluate the effect of a person-centered OT protocol on the prevention of delirium and the occupational performance of elderly patients admitted to the ICU. This is a randomized clinical trial with blinded assessment of the primary outcome (delirium). A total of 114 patients will be recruited and randomized to the intervention group, where care goals will be defined according to meaningful occupations and personalized cognitive stimulation will be based on patient´s topics of interest, in addition to the institutional standard protocol (ISP); or to the control group, which will receive only the ISP. To our knowledge, this will be the first randomized controlled trial with personalized occupational therapy interventions, as well as care goals, based on patients´ meaningful occupations for the prevention of delirium and improvement of occupational performance in critically ill elderly patients. This clinical trial is duly registered on the ClinicalTrials.gov platform (NCT06479031).