Michaelides was born in Cyprus to a Greek Cypriot father and English mother. He studied English literature at Trinity College, Cambridge.[2]
He studied psychotherapy for three years, and worked for two years at Northgate Clinic Adolescent unit, a mental health service for adolescents experiencing complex mental illness. This work provided material and inspiration for his debut novel The Silent Patient.[4]
"I made three films", Michaelides said of his screenwriting career, "and they went from bad to worse". After meeting someone at a party who told him that, having seen one of the films, "I didn’t expect you to be so interesting", he decided to give up on films and write a novel.[5]
Michaelides' debut novel, The Silent Patient,[6] was the No. 1 New York Times Bestseller of Hardcover Fiction in its first week[7] and was the bestselling hardback debut in the US for 2019.[4] It was a Sunday Times top 10 bestseller for seven weeks.[4] On Amazon.com, it was the No. 2 most sold for 2019 in their list of Most Sold Books in fiction[8] and named as their number one thriller of 2019.[4] It also won the Goodreads Choice Award for Best Mystery & Thriller of 2019,[9] was chosen as a Richard & Judy Book Club pick and as a Book of the Month in The Times.[4] It was shortlisted for a Barry for best debut and Barnes and Noble's Book of the Year.[4]Brad Pitt's production company, Plan B, is developing The Silent Patient as a film.[10]