Rex Billington was born in Auckland and attended Avondale College. He completed his Diploma in Physical Education at Otago in 1960 and a Diploma in Teaching at Christchurch Teachers' College in 1961. He was an accomplished sportsman who captained a New Zealand Rugby League Schoolboys team and later represented Otago, Auckland, Canterbury and South Island. He was a New Zealand Universities hammer throw champion. After teaching in New Zealand and Canada he gained an MA and in 1971 a PhD in Psychology and Education at the University of Iowa, USA.
After five years as an assistant professor in the University of Oklahoma and six years at the University of Dundee in Community and Occupational Medicine, Dr Billington was recruited by the World Health Organisation. For the next eighteen years till his retirement in 1999 he held senior posts in the WHO, in workforce development, as a Director in the Global Programme for HIV/AIDS and as a Director of Mental Health with overall responsibility for Mental Health Promotion and Policy, Mental Disorders and Neuroscience.
Following his return to New Zealand, Dr Billington was appointed a Professorial Fellow and an Adjunct Professor in Psychology at the Auckland University of Technology.