Sex-specific division of labour and the associated use of different subsistence techniques by males (e.g., hunting) and females (e.g., gathering) has played an important role in shaping human societies. Skills needed in adulthood are practiced in play during childhood and object play has been proposed to foster tool-use skills necessary for adult subsistence techniques. Here, we investigated sex differences in the ontogeny of object play in Tsimane children in Bolivia to understand its potential role in shaping gender-specific adult roles. We used observational data (>80,000 scan samples) from nine Tsimane communities collected between 2002 and 2007. We analysed age and sex differences in general play, object play and object types. Our results show that both general play and object play peaked in early to middle childhood (3.5-7.5 years of age), with boys spending more time playing. Moreover, boys engaged more with objects related to male-specific roles (e.g., hunting tools), while girls played more with objects related to female-specific roles (e.g., cooking tools). Our findings suggest that object play serves as an adaptive, culturally-embedded pathway to develop gender-specific adult skills. Studying developmental patterns of object play across human cultures enriches our understanding of the evolutionary contexts shaping divisions of labour.