Reef-building corals are mixotrophic organisms that obtain photosynthetically fixed carbon from their symbiotic association with algae of the family Symbiodiniaceae (from autotrophy) and assimilation of externally sourced organic compounds (heterotrophic uptake). Heterotrophic nutrition is highly beneficial to many coral species, particularly under environmental stress. Numerous experimental works have demonstrated that heterotrophy can enhance coral growth and fecundity, reduce mortality during a bleaching event, and accelerate post-bleaching recovery. Yet, the extent to which different coral species rely on heterotrophy remains largely complex and challenging to quantify. Understanding the importance of heterotrophy in coral resilience for the long-term survival of reef environments is critical. In an era largely focused on finding ways to limit the loss of coral reefs to global environmental change, the study of how heterotrophy can mitigate coral bleaching is timely. Here, we summarize our current understanding of the importance of heterotrophy for coral health and its contribution in terms of macro- and micronutrients on the survival of adult coral and early-life stages. This review highlights the urgency to further investigate the role of heterotrophy in coral resistance and resilience, and emphasizes the potential for identifying trophic niches and geographical areas that can serve as refuges from climate change.