Background <p>Dexmedetomidine (Dex) has promising lung-protecting effects. This study evaluated the effect of Dex on postoperative pulmonary complications (PPCs) in older patients undergoing abdominal laparoscopic surgery.</p> Methods <p>In this prospective, single-blinded, randomized controlled trial, 120 patients were assigned to the Dex or control group. All patients underwent surgical procedures with their designated anesthesia protocols. Patients in the Dex group received Dex intraoperatively, whereas those in the control group received the same volume of normal saline. The primary endpoints were the incidence and severity of PPCs. The secondary outcomes included blood gas analysis, breathing mechanics indices, postoperative recovery, vital capacity, pain scores, and the incidence of adverse events.</p> Results <p>The incidence of PPCs within 7 days after surgery was significantly lower in the Dex group (30.2% vs. 52.8%, <i>P</i> = 0.018). Notably, the incidence of hypoxemia was significantly lower in the Dex group (13.2% vs. 32.1%, <i>P</i> = 0.020). Intraoperative Dex administration enhanced improved blood gas outcomes, respiratory mechanics, and postoperative recovery.</p> Conclusions <p>Intraoperative infusion of Dex significantly reduced the incidence of PPCs within 7 days, especially hypoxemia, in older patients undergoing laparoscopic abdominal surgery.</p> Trial registration <p>Chinese Clinical Trial Registry (ChiCTR2300075746, Date of registration: 2023-09-14).</p>