Food waste is an issue throughout the food supply chain from production to consumption, especially in the later stages, such as retailing and final consumption. For the future of the developing world, changes in farming and retail practices are crucial. This study introduces a digital system for managing agricultural waste in Thailand that aims to encourage farmers and food retailers to sell their excess agricultural materials. The study’s objectives are as follows: (1) to explore factors that affect users’ behavioral intention to utilize an agriculture waste trading platform; (2) to compare the behavioral differences between farmers and retailers regarding their intention to use a digital platform for sustainable agriculture. Data were gathered from 570 fruit and vegetable sellers and farmers across five provinces in the northeastern region of Thailand. Structural equation modeling (SEM) was used to analyze the relationships between constructs based on the modified Unified Theory of Acceptance and Use of Technology (UTAUT2), and multigroup analysis (MGA) was employed to analyze differences in path coefficients across groups. The key findings revealed that social influence (SI) had a more significant impact on retailers compared to farmers, while facilitating conditions (FC), habits (HB), and privacy (PR) were necessary for both groups. Unlike retailers, farmers were also motivated by hedonic motivation (HM) from using the platform. Explicitly, retailers’ behavioral intentions were influenced by a more significant number of factors than those of farmers. This research suggests that policymakers should develop targeted marketing campaigns leveraging social influence for retailers, improve platform usability and security, and create incentives for habitual use to enhance platform adoption. Additionally, policymakers should promote engaging features for farmers, provide comprehensive education and training, and advocate for supportive policies and financial incentives. Strategic actions to facilitate the transition toward a circular economy will improve the environmental sustainability and economic resilience of the agri-food sector.