Delirium is a common complication in older patients after surgery and associated with poor early and long‐term outcomes. Dexmedetomidine is often used for perioperative sedation and analgesia. Many studies showed that perioperative dexmedetomidine reduced delirium after surgery in older patients; however, conflicting results were seen, which might be related to continuous unnecessary sedation and drug-related hypotension. Herein, we discussed the research findings of different clinical studies regarding the effect of dexmedetomidine on postoperative delirium, and provided suggestions for perioperative use of dexmedetomidine in clinical practice. When using dexmedetomidine during surgery, consider prophylactic norepinephrine infusion to reduce hypotension and bradycardia, and withdrawal in advance to guarantee timely awakening. For patients who are admitted to the intensive care unit, night-time infusion of low-dose dexmedetomidine may reduce delirium without increasing hypotension and bradycardia. For patients who are sent back to general ward after surgery, mini-dose dexmedetomidine in combination with opioid may be considered to improve analgesia and sleep quality without deepening sedation or increasing adverse events.