Background: The effect of delirium of hospitalized inpatients on post-discharge cognitive status and survival of older patients remains unclear, and little is known about the related risk factors of cognitive impairment after delirium. Objectives: To determine one-year survival of patients with delirium and cognitive dysfunction in elderly inpatients after initial hospital admission. Methods: This prospective cohort study was conducted on 100 patients with delirium admitted to a general hospital from October 2018 to November 2019. Cognitive dysfunction and death were the primary outcomes. The mini-mental state examination (MMSE) was used to measure cognitive function. Results: In this study, 12 patients died in hospital and cumulative three-month mortality was 40%. Finally, 60 patients were followed for one year. The one-year survival rate through the Kaplan-Meyer approach was 31%. The rate of one-year mortality was found with a significant association with underlying parameters, such as cancer (P = 0.008), cirrhosis (P = 0.04), trauma (P = 0.001), BUN ≥ 50 mg/dL (P = 0.02), Cr ≥ 1.2 mg/dL (P = 0.04), hypocalcemia (P = 0.0), and thrombocytopenia (P = 0.002). According to the MMSE scores, participants had normal cognition (46.7%), mild dementia (6.7%), moderate dementia (33.3%), and severe dementia (3.3%). The cognitive impairment showed a significant association with underlying parameters, such as pulmonary infections (P = 0.02), trauma (P = 0.02), and renal failure (P = 0.04). Conclusions: Assessment and screening for delirium is necessary in all older hospitalized inpatients. Cognitive measurement is effective to identify delirium, accelerate proper control, and decrease its negative effects. Family members should be trained and involved in care, particularly for monitoring of risk factors upon discharge.