Triadic social games are interesting from a cognitive perspective because they require a high degree of mutual social awareness. They consist of two agents incorporating an object in turn-taking sequences and require individuals to coordinate their attention to the task, the object, and to one another. Social games are observed commonly in domesticated dogs interacting with humans, but they have received only little empirical attention in nonhuman primates. Here, we report observations of bonobos (Pan paniscus) engaging in social games with a human playmate. Our behavioral analyses revealed that the bonobos behaved in many ways similar to human children during these games. They were interested in the joint activity, rather than the play objects themselves, and used communicative gestures to encourage reluctant partners to perform their role, suggesting rudimentary understanding of others' intentions. Our observations thus may imply that shared intentionality, the ability to understand and shares intention with other individuals, has emerged in the primate lineage before the origins of hominids.