Objective To conduct a scoping review of domestic and international research on hypoactive delirium in critically ill cardiac surgery patients，summarizing the current status，influencing factors，and assessment tools for hypoactive delirium in this population to inform clinical prevention and management strategies. Methods Using a scoping review framework，we systematically searched PubMed，the Cochrane Library，EMBASE，CINAHL，Web of Science，CNKI，Wanfang Database，VIP，and the China Biomedical Literature Database for studies on hypoactive delirium in critically ill cardiac surgery patients. The search covered the period from database inception to May 6，2025. Two researchers independently extracted and analyzed data. Results Twelve studies were ultimately included. The incidence of hypoactive delirium in critically ill cardiac surgery patients ranged from 21.57% to 92.00%. Clinical manifestations primarily included impaired verbal communication and disorientation，with most cases occurring within 72h postoperatively. Most studies conducted assessments around 08：00，with 1-3 evaluations per day. Diverse assessment tools were used，with the ICU Confusion Scale and Richmond Agitation-Sedation Scale being commonly employed. Independent influencing factors included history of alcohol consumption and duration of mechanical ventilation. Conclusion Hypoactive delirium exhibits a high incidence rate following cardiac surgery，with complex influencing factors and assessment tools lacking specificity. There is a need to develop targeted evaluation instruments and standardize assessment protocols. Concurrently，clinical manifestations，risk factors，and the onset or duration of low-activity delirium in critically ill cardiac surgery patients should be prioritized for early prevention and management to improve patient outcomes.