Douglas Hanahan received a bachelor's degree in physics from the Massachusetts Institute of Technology and a Ph.D. in biophysics from Harvard University. He worked at Cold Spring Harbor Laboratory in New York, initially as an itinerant Harvard graduate student and Harvard Junior Fellow, and then as a faculty member. Subsequently, he spent two decades as a Professor at the University of California San Francisco before moving to EPFL.

Hanahan was elected to the American Academy of Arts & Sciences, the US National Academies of Sciences and of Medicine, the European Molecular Biology Organization, and the Academy of the American Association for Cancer Research, which honored him with its Lifetime Achievement award. He received an honorary degree from the University of Dundee.

Hanahan developed methods that markedly facilitated the molecular cloning of mammalian genes in bacteria. Then he pioneered genetic engineering of mice endowed to develop organ-specific tumours. His research program has centered on using mouse models of human cancer to illuminate determinants of multistep tumour development and to develop mechanism-guided therapeutic strategies aiming to improve the treatment of human cancers.