Prior to his retirement on 1st January 2012 Professor Gudjonsson was the Head of Forensic Psychology Services for Lambeth Forensic Services and Medium Secure Services at the South London and Maudsley NHS Trust (SLaM). He is a Chartered Psychologist and a Fellow of the British Psychological Society. Professor Gudjonsson is a registered practitioner (clinical and forensic) with the Health & Care Professions Council (HCPC) and an honorary consultant clinical and forensic psychologist at Broadmoor Hospital.

In April 2009 the British Psychological Society presented Professor Gudjonsson with a Lifetime Achievement Award for his exceptionally significant and sustained contribution to the practice of psychology. He was awarded the European Association of Psychology and Law (EAPL) Life Time Achievement Award for 2012. Professor Gudjonsson was appointed a Commander of the Order of the British Empire (CBE) in the Queen’s Birthday 2011 Honours List for services to clinical psychology.