After attending the University of Cambridge and Middlesex Hospital Medical School Brian Greenwood qualified in medicine in 1962. Following house-officer appointments in London, he spent three years in Western Nigeria at University College Hospital, Ibadan as a medical registrar and research fellow. This period in Nigeria was followed by three years in the U.K. training in clinical immunology. In 1970, he returned to Nigeria to help establish a new medical school at Ahmadu Bello University, Zaria, where he developed his research interests in malaria and meningococcal disease whilst continuing to teach and practice clinical medicine.

In 1980, Dr. Greenwood moved to the U.K. Medical Research Council Laboratories in The Gambia which he directed for the next 15 years. In The Gambia, he helped to establish a multi-disciplinary research program which focused on some of the most important infectious diseases prevalent in The Gambia and neighboring countries; these diseases include malaria, pneumonia, measles, meningitis, hepatitis and HIV2.

In 1996, Dr. Greenwood was appointed to the staff of the London School of Hygiene and Tropical Medicine where he is now Manson Professor of Clinical Tropical Medicine and Director of the Gates Malaria Partnership which supports a program of research and capacity development in many countries in Africa directed at improving treatment and prevention of malaria.