Warren married Winifred Theresa Warren (née Williams) in the early 1960s and together they had five children. Winifred Warren went on to become an accomplished Psychiatrist. Following her death in 1997, Warren retired from Medicine.
In 1963, Warren was appointed Honorary Clinical Assistant in Pathology and Honorary Registrar in Haematology at Royal Adelaide Hospital. Subsequently, he lectured in pathology at Adelaide University, then took up the position of Clinical Pathology Registrar at the Royal Melbourne Hospital. In 1967, Warren was elected to the Royal College of Pathologists of Australasia and became a senior pathologist at the Royal Perth Hospital where he spent the majority of his career.
In 2005, Warren and Marshall were awarded the Nobel Prize in Medicine.
An Australian documentary was made in 2006 about Warren and Marshall's road to the Nobel Prize, called "The Winner's Guide to the Nobel Prize". He was appointed a Companion of the Order of Australia in 2007.
