Duncan Watkinson was born in Hammersmith, London. His father, Douglas Watkinson is a writer of both television and theatre, one of the original writers of The Midsomer Murders and the creator of the Nathan Hawk murder mystery novels. His mother was a stage manager at the Theatre Royal in York. He grew up in a small village near Oxford and attended Aylesbury Grammar School for Boys before moving to London in 1999. He trained at The Royal Central School of Speech and Drama in Swiss Cottage, London.