A systematic review was conducted of randomized trials of workplace weight management interventions, including trials with dietary, physical activity, environmental, behavioral, and incentive-based components. Main outcomes were defined as change in weight-related measures. Keywords related to weight management and workplace interventions were used to search relevant databases, and 23 eligible studies were reviewed in detail using a data extraction form and quality assessment checklist. The trials were conducted mainly in the USA and Europe, with four additional countries represented. Interventions were mostly multicomponent and were implemented in both sexes and in a range of employment categories. Intervention effectiveness appeared unrelated to region of the world and was highest in 6-12-month trials. The results ranged widely from clinically significant 8.8-kg weight loss in one trial to less effective than the control treatment in others. Some workplace interventions achieve clinically significant benefits, and further studies are needed to replicate those results in wider sociocultural and geographical contexts.