The COVID-19 pandemic is threatening health systems worldwide, requiring extraordinary efforts to contain the virus and prepare health care systems for unprecedented situations. In this context, the entire health care workforce must be properly trained to guarantee an effective response. Just-in-time training has been an efficient solution for rapidly equipping health care workers with new knowledge, skills, and attitudes during emergencies; thus, it could also be an effective training technique in the context of the response to the COVID-19 pandemic. Because of the unexpected magnitude of this health crisis, the health care workforce must be trained in two areas: (1) basic infection prevention and control, including public health skills that are the core of population-based health management and (2) disaster medicine principles, such as surge capacity, allocation of scarce resources, triage, and the ethical dilemmas of rationing medical care. This perspective reports how just-in-time training concepts and methods were applied in a tertiary referral hospital in March 2020, during the COVID-19 pandemic in Northern Italy, one of the hardest hit places in the world.The COVID-19 just-in-time training was designed to provide hospital staff with the competencies they need to work proficiently and safely inside the hospital, including an understanding of the working principles and standard operating procedures in place and the correct use of personal protective equipment. Moreover, this training was intended to address the basic principles of disaster medicine applied to the COVID-19 pandemic. Such training was essential in enabling staff to rapidly attain competencies that most of them lacked because disaster medicine and global health are not included in the curricula of Italian medical and nursing schools. Although a formal evaluation was not performed, this is a useful example of how to create just-in-time training in a large hospital during a crisis of an unprecedented scale.