Background: Timely diagnosis and effective treatment of delirium, a clinical syndrome, significantly impact the outcomes of patients in intensive care units (ICUs). Despite its significance and prevalence, delirium continues to be underdiagnosed. This study aims to determine the knowledge and capability of ICU nurses in Iraq in recognizing delirium syndrome. Methods: This descriptive cross-sectional study was conducted on 154 nurses working in the ICUs of hospitals in Babylon, Al-Diwaniyah, and Karbala cities, Iraq, in 2022. The subjects were recruited by the census. The study data were collected using a demographic questionnaire, case vignettes, and the delirium knowledge questionnaire (DKQ) to assess participants’ characteristics, delirium recognition, and delirium knowledge. The data were analyzed using an independent t-test and Pearson correlation coefficient in SPSS software, version 22. The significance level was set at P<0.05. Results: The Mean±SD score of nurses’ overall knowledge was 46.73±14.34. The Mean±SD score for their understanding of delirium’s incidence, symptoms, signs, and effects was 43.57±17.70, whereas the Mean±SD score for knowledge of its risk factors and causes was 49.7±18.74. Their overall ability to recognize delirium had a Mean±SD score of 1.44±1.13. There was a significant relationship between knowledge of delirium, participation in a delirium training course (P=0.008), and work experience in ICUs (P=0.046). Conclusion: Given the results of our study, it is crucial to develop plans for increasing the knowledge and recognition ability of ICU nurses in Iraq regarding delirium.