Wilf was born in Alexandria, Egypt, from British parents on April 23, 1931.  He was educated at the British Boys’ School, attended the University of Alexandria as a free auditor and graduated with a BSc Special Honours degree in Chemistry (External, University of London) in 1953. He left Egypt and was trained in organic stereochemistry at Bedford College (University of London), submitting a PhD thesis in 1955. He travelled to Melbourne in 1956, was appointed Research Officer at ICIANZ Central Research Laboratories researching plant growth substances for two years, then spent a year as Senior Demonstrator in Organic Chemistry at the University of Melbourne. Wilf worked in the John Curtin School of Medical Research (JCSMR), Australian National University for 36 years.  He was first appointed to the Department of Medical Chemistry in 1960, then transferred to the Department of Biochemistry and Molecular Biology in 1972.  During the first eight years, he studied the physicochemical properties of heterocyclic compounds with relevance to pharmaceutical drugs, gaining a DSc (Lond) degree at the age of 36. In the subsequent 28 years, he worked on the biochemistry and molecular biology of enzymes and their cofactors that are defective in children with inborn errors of metabolism. This involved enzyme purification, kinetics and mechanisms, cloning, site directed mutagenesis and gene expression; finding that the kinetics of the mutated enzymes corresponded with the severity of the inherited disease. Apart from many administrative duties, he has supervised several research students, research and postdoctoral fellows and a large number of visiting students, visitors and technical staff. Since retirement, he has been a Visiting Fellow in the JCSMR.  Wilf has written 13 reviews, four books (one of which, Purification of Laboratory Chemicals, is a best seller and is in its eighth edition in 2017), in addition to a large number of refereed research publications (see Researchgate).

Dr Armarego was awarded FRSC (1963), CChem, FRACI (1972), the Archibald D. Ollé Prize (1968) and Worldwide Who’s Who Professional of the Year (2014) representing Medical Research and Education. In the 2019 Australian New Year Honours List Wilf Armarego was awarded a Member of the Order of Australia (AM) for ‘significant service to biochemistry and molecular biology’.

Some of his work is summarised in "Pteridine Chemistry and Biology' by W.L.F.Armarego, "The John Curtin School of Medical Research, The first fifty Years 1948-1998" Eds F. Fenner and D.R.Curtis, Brolga Press, Gundaroo, Australia, pp. 360-363, 2001; ISBN 1 875495 33 9.