Corticosterone (CORT) has long been considered an important and necessary hormone for avian migration. Exactly how CORT facilitates migration, however, is under debate. We examined the literature to evaluate three non-mutually exclusive hypotheses for CORT’s role in migration: 1) CORT facilitates physiological preparations for migration, 2) CORT stimulates departure from origin or stopover sites, and 3) CORT supports long-distance migratory flight. To test these hypotheses, we analyzed both wild and captive studies, including observational studies and experimental manipulations, that presented data relevant to predictions of each hypothesis. Overall, we found weak support for the hypothesis that CORT helps birds physiologically prepare for migration, and moderate support for the hypothesis that CORT stimulates migratory departure. We were unable to adequately test the hypothesis that CORT helps maintain long-distance flight, as few studies have measured CORT in actively flying birds. We provide recommendations for approaches that could be used in future studies to address gaps in our understanding of CORT’s role in migration.