AbstractLoneliness is a salient risk factor for obesity, emotional eating, and poor diet. Because adolescents and parents are embedded within a family unit, their experiences of loneliness may be associated with both their own and one another's behaviors. To examine the extent to which parent and child loneliness predict body mass index (BMI) and eating in parents and adolescents, an actor–partner interdependence model of loneliness, eating, and BMI in adolescent–parent dyads was analyzed. There were actor effects among adolescents such that greater loneliness was positively associated with emotional eating and BMI‐z, and there was an actor effect among parents such that higher loneliness was positively related to emotional eating. There was a partner effect among adolescents such that greater parental loneliness was positively associated with adolescent emotional eating, and there was a partner effect among parents such that higher adolescent loneliness was positively associated with parental emotional eating. There were several actor–partner effects for loneliness and junk food in dyads with boys. Findings highlight the importance of dyadic models of loneliness in adolescent–parent dyads.