Extreme climatic events, including marine heatwaves (MHWs), are altering ecosystems globally, often with profound socioeconomic impacts. We examine how MHWs have affected the provision of ecosystem services and evaluate the socioeconomic consequences for human society. Ecological impacts range from harmful algal blooms and mass mortality events to reconfigurations of entire ecosystems, affecting provisioning, habitat, regulating, and cultural ecosystem services globally. Reported economic costs of individual MHW events exceed US$800 million in direct losses or >US$3.1 billion in indirect losses of ecosystem services for multiple years. However, biological responses to MHWs can also increase human-ocean interactions, providing opportunities for coastal societies. Our study provides a global perspective on the far-reaching impacts of MHWs on human societies and highlights the urgent need to develop robust approaches to mitigation and adaptation.