When people judge acts of kindness or cruelty, they often look beyond the act itself to infer the agent’s motives. These inferences, in turn, can powerfully influence moral judgements. The mere possibility of self-interested motives can taint otherwise helpful acts, whereas morally principled motives can exonerate those behind harmful acts. In this Review, we survey research showcasing the importance of inferred motives for moral judgements, and show how motive inferences are connected to judgements of actions, intentions and character. This work suggests that the inferences observers draw about peoples’ motives are sufficient for moral judgement (they drive character judgements even without actions) and functional (they effectively aid observers in predicting peoples’ future behaviour). Research that directly probes when and how people infer motives, and how motive properties guide those inferences, can deepen our understanding of the role of inferred motives in moral life.