Purpose <p>The impact of higher intraoperative oxygen administration increases the risk of postoperative pulmonary complications (PPCs) remains uncertain. This study aimed to investigate whether high supraphysiological oxygen exposure during abdominal surgery is associated with the development of PPCs.</p> Methods <p>We conducted a multi-center prospective cohort trial of adults scheduled for abdominal surgery under general anesthesia lasting at least two hours. Supraphysiological oxygen exposure was quantified as the area under the curve of the FiO₂ above the 21% threshold while the corresponding SpO₂ remained above 92%. The primary outcome was a composite of pulmonary complications within the first 7 postoperative days. Multivariate logistic regression was used to assess the association between intraoperative oxygen exposure and PPCs.</p> Results <p>Among the 660 included patients (mean age, 58&#xa0;years; 275 [41.7%] women; 468 [70.1%] at intermediate or high risk of PPCs), 163 (24.7%) experienced PPCs within the first 7 postoperative days. After adjusting for confounders, higher supraphysiological oxygen exposure was independently associated with PPCs (adjusted odds ratio, 1.21 [95% confidence interval, 1.09–1.35], <i>P</i> &lt; 0.001).</p> Conclusions <p>In adult patients undergoing abdominal surgery under general anesthesia, intraoperative supraphysiological oxygen exposure was associated with an increased risk of PPCs.</p>