Green products are among the widely used products worldwide due to their environmental benefits. However, information on the consumers’ purchase intention towards green products in developing countries, such as Thailand, is lacking. This study aims to investigate Thai consumers who are aged over 18 years, and whose base education is high school, on purchase intention for green products by using an extended framework of the theory of planned behavior (TPB). We derived and examined the model through structural equation modeling in a sample of 483 respondents in Thailand. The findings of this model indicated that consumer attitude, subjective norm and perceived behavioral control have significant positive influences on the purchase intention for green products. Furthermore, our results indicated that environmental concerns have a significant effect on attitude, perceived behavioral control and purchase intention for green products, but subjective norm. Moreover, environmental knowledge had no significant effect on the purchase intention for green products. Instead, it had a distinct indirect effect through attitude towards purchasing green products, subjective norm and perceived behavioral control. The findings from this study contribute to improving the understanding of intention to purchase green products, which could play a major role towards sustainable consumption.