Vietnam has introduced Integrated Pest Management (IPM) for more than thirty years. However, it has not been adopted and diffused widely. Thus, both the government and non-government extension programs have promoted the practice of IPM or integrated IPM with other programs such as Vietnamese Good Agricultural Practice (VietGAP) recently in Vietnam to help farmers pursue sustainable agriculture with market-oriented. This research aims to identify the significant factors affecting farmers’ decision and intention to apply IPM in the case of longan in the Mekong Delta, Vietnam. This research applied theory of planned behavior (TPB) to build the models to examine factors influencing farmers’ behavior and intention to adopt IPM using binary logistic regression. The results show that farmers perceived the benefits of applying IPM to help them to reduce the production cost, increase productivity, reduce health risks to sprayers, community and end consumers, and ecological functions to the soil, animals, and aquatic environment. The importance of the belief on the effectiveness of IPM leads to the close relationship between farmers’ intention to adopt IPM and the community-based IPM programs. Economic benefits of adopting hypothetical IPM programs are the most significant factors controlling farmers’ intention to practice IPM. The success of previous extension programs would generate the best belief to farmers to disseminate agricultural technologies in Vietnam.