The complex life history of sea turtles presents challenges for researchers. These slow-growing, long-lived reptiles occupy several habitats throughout their life cycle, including oceanic environments where they are difficult to study. Consequently, much research on sea turtle biology has focussed on the nesting environment. Yet, to effectively manage sea turtle populations, the documentation of processes such as growth, maturation and reproductive output is critical to understanding their population dynamics. Dynamic Energy Budget (DEB) theory provides a mechanistic framework for investigating such processes. Here we developed a full life cycle DEB model for a green turtle (Chelonia mydas) population from Western Australia, where the model was based primarily on data collected on the embryonic life stage. The model provided a good fit to empirical data, including the limited data on juvenile and adult growth, and suggested that it is practical to investigate full life cycle energetics based on embryonic data that are comparatively easy to collect. Maternal effects on embryonic development and patterns of energy allocation throughout the life cycle were inferred from the DEB model. This is the first DEB model developed for C. mydas, and its potential applications include demonstrating how maturation, maintenance and reproduction of wild individuals depend on food availability and temperature. Such applications are especially valuable for understanding future impacts of climate change, and how best to manage this iconic species that plays a key role in marine ecosystems across the globe.