Disinsection of aircraft and other conveyances is recommended to prevent the international spread of disease-carrying mosquitoes. A systematic review synthesized the effectiveness of adult mosquito disinsection aboard international air, marine, and land conveyances, using literature available up to 31 May 2025. Nineteen experimental trials, nine of which included an unexposed control arm, were synthesized. The studies were generally of poor quality with high risk of bias, and adherence to WHO guidelines was 33.30% (range: 18.20–60.5%). Across comparator trials of aircraft disinsection, the odds of mosquito mortality in the treated groups compared to control groups was 163.60 (95% CI 147–182), and the relative risk of mosquito death was 14.24 (95% CI 12.99–15.63). The direction of effect was consistent across mosquito species, methods of disinsection, types of aircraft, and insecticides, though the magnitude of the effect varied widely. The only WHO-recommended insecticide tested in a controlled trial was 2% d-phenothrin, which demonstrated an odds ratio of 171.70 (95% CI 139.10–212) and a relative risk of 20.08 (95% CI 16.53–24.43) for mosquito mortality. The lack of adherence to WHO guidelines raises uncertainty about the real-world effectiveness of disinsection.