Objective: To formally test a hierarchy of effects model linking exposure to television (TV) advertising for unhealthy foods with child body weight through purchase requests, purchases, and consumption. Design: A nationally representative cross-sectional online study in the United Kingdom. Participants: A total of 2,260 parent-child dyads (children aged 7–11 years) recruited via online research panel; 55.7% boys, mean age 8.9 ± 1.4 years, mean body mass index z-score 1.25 ± 2.1. Main Outcome Measures: Parents reported on child TV exposure and child height and weight. Children self-reported their frequency of (1) pestering for advertised foods, (2) purchase of unhealthy foods, and (3) consumption of unhealthy foods. Analysis: A structural equation model was applied to data. Results: As predicted, commercial TV exposure was indirectly associated with children's body mass index through purchasing and consumption through purchase requests. It was also directly associated with children's purchase requests, purchasing, and consumption of unhealthy foods. Associations between noncommercial TV and behavior or body weight outcomes, when found, were significantly weaker than for commercial exposure. Conclusions and Implications: This study provides insight into the likely behavioral pathways underpinning the effects of food marketing on diet and potentially body weight in children. Future longitudinal analyses would provide insight into causal inferences.