Background: The World Health Organisation Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. We aimed to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients undergoing emergency laparotomy. Methods: In two multinational cohort studies, adults undergoing emergency laparotomy were compared to those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results: Of 12296 included patients from 76 countries, 4940 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use prior to emergency laparotomy was more common in high-HDI countries (2455/2741, 89.6%) compared with middle- (753/1242, 60.6%; OR 0.17, CI 0.14-0.21, p<0.001) and low-HDI countries (363/860, 42.2%; 0.08, 0.07-0.10, p<0.001). Checklist use was more frequent in emergency laparotomy than in elective surgery in high-HDI countries (risk difference 9.4%, CI 6.9% to 11.9%, p<0.001) but the relationship was reversed in low-HDI countries (-12.1%, -17.3% to -7.0%, p<0.001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, CI 0.50-0.73, p<0.001). The largest absolute benefit was seen in emergency surgery in low- and middle-HDI countries. Conclusions: Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality, yet its use in low-HDI countries was half that of high-HDI countries. The greatest absolute gains may be made by focussing patient safety programmes in emergency settings in low- and middle-HDI countries.