Importance: Robot-assisted surgery (RAS) is increasingly used for abdominal procedures; however, postoperative pulmonary complications (PPCs) are more frequent in patients undergoing RAS compared with patients undergoing conventional laparoscopic surgery (CLS). Objective: To compare the incidence of PPCs after CLS and RAS and to determine which patient-, surgery-, and anesthesia-related factors are associated with PPCs. Design, Setting, and Participants: This cohort study used the Laparoscopic and Robot-Assisted Surgery (LapRAS) database, a pooled dataset containing individual patient data of 2 worldwide prospective cohort studies: the Local Assessment of Ventilatory Management During General Anaesthesia for Surgery (LAS VEGAS) study and the Assessment of Ventilatory Management During General Anesthesia for Robotic Surgery and Its Effects on Postoperative Pulmonary Complications (AVATaR) study. Data were collected from adult patients requiring intraoperative ventilation during general anesthesia for CLS or RAS surgical procedures from 163 centers and 31 countries in the Americas, Europe, the Middle East, and North Africa from January 2013 to March 2019. Data were analyzed from December 2023 to October 2024. Exposures: Type of surgical approach (CLS vs RAS), duration of intraoperative ventilation, and intensity of mechanical ventilation, assessed using the 4 times the driving pressure (DP) plus respiratory rate (RR) estimator (4DP + RR). Main Outcome and Measures: The primary outcome was occurrence of 1 or more PPCs in the first 5 postoperative days. Mixed-effects logistic regression assessed associations with PPCs; mediation and matched cohort analyses served as sensitivity analyses. Results: A total of 2738 patients (median [IQR] age, 56 [41-66] years; 1456 female [53.1%]) were included. PPCs occurred in 172 of 903 patients (19.0%) in the RAS group and 174 of 1835 patients (9.5%) in the CLS group (P <.001). Duration of intraoperative ventilation was longer in RAS compared with CLS (median [IQR] duration, 219 [180-270] vs 95 [68-145] minutes; P <.001) and the intensity of mechanical ventilation was higher (median [IQR] intensity, 84 [69-100] vs 72 [60-87] 4DP + RR; P <.001). PPCs were independently associated only with duration of ventilation (adjusted odds ratio [aOR], 1.49; 95% CI, 1.33-1.66; P <.001), not with the surgical approach (ie, RAS vs CLS; aOR, 1.35; 95% CI, 0.72-2.54; P =.35) nor the intensity of ventilation as measured by 4DP + RR (aOR, 1.01; 95% CI, 1.01-1.01; P =.21). A post hoc analysis showed a more pronounced association of intensity of ventilation in surgical procedures of shorter duration. Conclusions and Relevance: In this cohort study, patients who received RAS vs CLS had a higher incidence of PPCs and received longer and more intense mechanical ventilation; however, only the duration of ventilation rather than intensity of ventilation or type of surgical approach (ie, RAS vs CLS) was independently associated with the occurrence of PPCs, indicating that the longer duration of ventilation in RAS underlies the higher incidence of PPCs observed in those who undergo this type of surgery.