Eating in response to external food cues (i.e., external eating) and internal emotional experiences (i.e., emotional eating) are associated with obesity. While external and emotional eating co-occur, little is known about how external food cue responsiveness may interact with internal emotional cues to influence eating episodes in adolescents. The current study examined how trait-level external food cue responsiveness modulates momentary associations between affective states and eating in adolescents. Participants were drawn from a prior study of siblings (N = 78; ages 13–17) who completed an ecological momentary assessment protocol to assess eating episodes and affective states. External food cue responsiveness was determined by comparing energy consumption following presentation of an appetizing food (pizza) on one day and a control activity (reading) on another day. Generalized linear mixed models examined positive and negative affective states, cue responsiveness, and their interactions as predictors of the likelihood of eating. The relationship between affective states and likelihood of eating was stronger among adolescents with higher versus lower external food cue responsiveness. Among adolescents with higher cue responsiveness, endorsing negative affect was associated with a lower likelihood of eating, whereas endorsing positive affect was associated with a higher likelihood of eating (within-person effects). Findings suggest that high sensitivity to external food cues and greater proclivity for emotional eating may be likely to coincide such that any cue, internal or external, is likely to disrupt sensitivity to internal hunger and satiety signals. Future studies are needed to elucidate how sensitivities to internal and external cues may interact to influence obesity risk.