Dunnill self-learned French and German, and obtained his BSc in chemistry from the University College London.
Dunnill continued his study and research at the Royal Institution (RI) where he obtained his PhD in protein crystallography under Nobel Prize laureate Lawrence Bragg.
He worked at the Sir John Cass College (now the London Guildhall University).
Dunnill was a founder of the Advanced Centre for Biochemical Engineering at UCL.
Dunnill was elected to the Biotechnology and Biological Sciences Research Council (BBSRC) in 1994.