Within the past few decades, the academic discipline of public health has taken root in universities around the world. As a young and multidisciplinary field with a dual-research/practice focus and a tradition that emphasises method development, the use of theory in public health research has often been neglected. In this article, we argue that explicit utilisation of theory is crucial to further the development of public health as an academic discipline. By examining three core areas of academic activity at universities—education, research and public outreach—we illustrate the role theory plays in establishing public health as an independent research discipline. We discuss the importance and benefits of including theoretical reasoning in teaching, research articles and communication with non-academic audiences. We also highlight the role of postgraduate students and junior researchers who, thanks to a combination of experience and receptiveness, play an important role in developing public health theory. We believe that a key to a successful process of establishing public health as an academic discipline lies in the development of a transdisciplinary approach to the research subject. This will equip public health researchers with appropriate tools to take on the public health challenges of the future.