The science, technology, engineering, mathematics (STEM) doctorate is the established entry qualification for a scientific research career. However, contemporary STEM doctoral graduates assume increasingly diverse professional paths, with many forging non-academic careers. Using the UK as an example, the authors suggest that the STEM PhD fails to adequately prepare students for the complexity of their future professional lives. They argue that a neglect of the development of professional identity is damaging, even to those who pursue a research career, because the landscape of contemporary science has transformed. The authors propose three reforms to the STEM doctorate to aid the development of professional identity and equip students with a more flexible understanding of becoming and being a researcher. The reforms will boost the resilience of doctoral graduates as they embark upon their varied career trajectories, and therefore assure the continued cultural, social and economic contributions of these highly skilled individuals.