Abstract This article investigates the predictors of purchase behavior of the generation Z (Gen Z) in the Vietnamese organic food sector. We proposed a research model by extending the theory of planned behavior (TPB) with the motivation–opportunity–ability (MOA) framework to address the gap between purchase intention and behavior in the organic food market. Data from a self-administered online survey with 426 respondents living in the three biggest cities of Vietnam were analyzed in SmartPLS software to test proposed hypotheses. Our findings show that trust is the most crucial factor affecting the purchase behavior of Gen Z in the Vietnamese organic food sector. Notably, perceived barriers (PB) were found to positively influence purchase behavior. The present study suggests the organic food producers and suppliers to change their marketing strategies and policies in response to the demanding Vietnamese Gen Z.