Uncertainty is a fundamental aspect of human social life. Based on fruitful findings, the current review aims to establish a schema that outlines the relationship between uncertainty and human social decision-making: the influences of uncertainty on social decision-making (mainly prosocial behaviors) and the strategies commonly employed to reduce social uncertainty. Human prosocial behaviors are modulated by both social and nonsocial uncertainty. Specifically, uncertainty decreases prosocial behaviors by providing moral wiggling room or promoting loss aversion but also helps maintain relationships by mitigating negative interactions. Moreover, impression formation, impression updating, and compliance with social norms are crucial strategies for coping with social uncertainty, but they are subject to various biases. Finally, we highlight some important issues that need to be addressed in future studies. In summary, the current review deepens our understanding of the role of uncertainty in social behaviors.