Objectification—the psychological phenomenon of relegating people to the status of objects—is associated with a host of negative consequences, from diminished cognitive performance to heightened risk of danger. Girls and women constitute the primary targets of objectification; thus, these harms fall disproportionately on them. Despite the severity of its impacts, however, the developmental origins of such gender-based objectification have received little empirical attention, limiting our grasp of this phenomenon both theoretically and practically. In the present research, we sought to address this gap on two fronts. First, we tested whether and to what extent gender-based objectification gets applied to young targets (n = 237 adults), and second, we tested when this tendency first begins to develop in young perceivers (n = 352 children, ages 5-10 years). We found robust evidence that adults engage in gender-based objectification of young children: in both a speeded categorization task and a property attribution task, adults’ concepts of girls and boys overlapped with their concepts of objects and humans, respectively. Children themselves also showed evidence of gender-based objectification, but in a more limited manner: boys, but not girls, engaged in gender-based objectification, and only at the level of their categorizations. Together, these findings suggest that gender-based objectification extends to perceptions of young children and begins to develop early in childhood—indicating that the consequences of gender-based objectification may be far larger in scope, and earlier emerging, than previously assumed.