Green food has been introduced into the market for several years. Nevertheless, most Thai consumers do not commonly purchase green food in their daily routine. This research article aims to identify the market segments and significant factors affecting green food purchase intention in Thailand based on the theory of planned behavior. It employed a sample of 458 green food consumers in five regions of Thailand. Based on the Food-Related Lifestyle model, we used cluster analysis to classify the market segments. Additionally, we employed a multi-group structural equation modeling technique to explore and compare customers’ behaviors in different segments. The results demonstrated two primary market segments for green food products, including (1) non-green consumers and (2) green consumers. The findings indicate that green consumers’ self-realization related to environmental issues positively affects their attitude and purchase intention, while non-green consumers reveal none of these relationships. Surprisingly, social norms related to green food consumption influence non-green consumers’ attitudes toward green food more than it does toward green consumers. This research paper enlarges the understanding of Thailand’s green food market regarding the market segments (non-green and green consumers). Furthermore, it points out implications on how marketing practitioners may penetrate those segments.