Cognitive impairment and older age are major risk factors for postoperative delirium. Professional societies have advocated preoperative screening to identify at-risk individuals for implementation of interventions, which have moderate effectiveness in preventing delirium. However, it remains unclear from the guidelines whether screening should be completed routinely for all older individuals or targeted, and also which specific screening tool is preferred. In addition, the responsibility for screening remains undesignated in the guidelines provided. We reviewed the benefits and risks of routine screening. We also performed a cost-benefit analysis of routine screening (versus no screening). Furthermore, we summarised the sensitivities and specificities of commonly used screening tools and reviewed evolving screening tools that may have an increasing role in future practice. We concluded that routine screening is useful and appears to be cost-effective for reducing postoperative delirium, with a cost-benefit ratio of 2.89 (adjusted ratio of 2.34), and has additional advantages over other approaches such as targeted screening or routine intervention.