Human interactions with social robots inevitably involve anthropomorphism. Concerns have arisen regarding whether robot anthropomorphism is accompanied by negative human relationships. In particular, limited empirical research suggests that the more humanness people attribute to nonhuman agents (e.g., social robots), the more they deny to humans, thus implying a positive association between robot anthropomorphism and dehumanization. From a motivational perspective, we examined whether social connectedness—the perception of closeness with others—may expand the scope of agents deserving to be treated as having humanness, thereby tempering the possible positive association between robot anthropomorphism and dehumanization. Across three studies (two preregistered) conducted with Chinese participants, we induced social connectedness and measured anthropomorphism of social robots and dehumanization of certain individuals. Robot anthropomorphism negatively predicted dehumanization on human nature traits and the mental capacity to feel among participants induced to feel social connectedness (but not social neutrality or disconnectedness). Although their generalizability across diverse cultures warrants further investigation, our findings offer novel theoretical insights into humanness attribution, and practical implications for promoting social cohesion in the era of intelligent machines.