Background and objective: Despite the availability of assessment tools for identifying and managing delirium in clinical settings, most cases remain undiagnosed, which demands the importance of conducting educational sessions. There is a necessity to understand why ICU nurses are unable to assess delirium in ICU patients, and there is a need to establish the best practice to promote patient safety. The descriptive cross-sectional research design aimed to assess the ICU nurses’ perception, knowledge, and Perceived barriers to delirium assessment, assess the association between qualifications and previous education regarding delirium to their knowledge and perception, and evaluate the association between ICU nurses' experience and total scores of knowledge and perception.Methods: A total 105 ICU nurses were selected from one of the tertiary hospitals in the Sultanate of Oman. Socio-demographics about ICU nurses’ knowledge, perception of delirium, and barriers to proper delirium assessment were collected by using an online self-administrative survey after obtaining consent. Data were statistically analyzed for central tendencies and level of dispersion (mean, range, and standard deviation).Results: The result of this study illustrated that 60.2% of ICU staff nurses have a moderate perception of the importance of delirium assessment in ICU. The majority of the nurses are females who held bachelor’s degrees with experience of six to ten years in the critical care field.Conclusions: The finding in this study illustrated that most of the staff nurses have previous training regarding delirium. However, there are gaps in delirium assessment, perception, and knowledge in ICU. Therefore, appropriate education is required to increase delirium identification, skill, and knowledge.