This cross-sectional study examined the mediating effect of the theory of planned behavior (TPB) and the moderating role of perceived parental control within the context of adolescents' junk-food consumption. Adolescents (N = 739) were selected using a cluster-stratified randomized sampling method. Social cognitions, perceived parental control, and junk-food consumption were assessed through self-administered questionnaires. Results revealed both direct and indirect effect of perceived parental control within TPB. Additionally, impact of intention was not moderated by perceived parental control. TPB explained 28% and 12% of the variance in intention and junk-food consumption, respectively. This study identified somewhat both the why and how of junk-food consumption in Iranian female adolescents.