Background: The incidence of in-hospital adverse events is about 10%, with a majority of these related to surgery, and nearly half considered preventable events. In attempts to improve patient safety, the World Health Organization (WHO) developed a checklist to be used at critical perioperative moments. This meta-analysis examines the impact of the WHO surgical safety checklist (SSC) on various patient outcomes. Methods: A comprehensive search of all published studies assessing the use of the WHO SSC in patients undergoing surgery was conducted. Studies using the WHO SSC in any surgical setting, with pre-implementation and post-implementation outcome data were included. The incidence of patient outcomes (total complications, surgical site infections, unplanned return to the operating room (OR) within 30 days, and overall mortality) and adherence to safety measures were analyzed. Results: 10 studies involving 51,125 patients (27,490 prior to implementation and 23,635 after implementation of the WHO SSC) were analyzed. The implementation of the WHO SSC significantly reduced the risk of total complications by 37.9%, surgical site infections by 45.5%, unplanned return to OR by 32.1%, and mortality by 15.3%. Increased adherence to safety measures including airway evaluation, use of pulse oximetry, prophylactic antibiotics when necessary, confirmation of patient name and surgical site, and sponge count was also observed. Conclusions: The use of the WHO SSC is associated with a significant reduction in post-operative complication rates and mortality. The WHO SSC is a valuable tool that should be universally implemented in all surgical centers and utilized in all surgical patients.