Harold Riley was born in Salford in 1934, his father was a jazz musician and his mother was a school teacher. At the age of 17 he won a scholarship to the Slade and went on to study in Florence and Spain before returning to Salford, where he has lived ever since. As a student he became a good friend of fellow Salfordian L. S. Lowry.
Riley developed his reputation as a portraitist of many rich and famous people including popes, presidents and royalty including Nelson Mandela and Pope John Paul II. His sporting works include golf (Henry Cotton, Jack Nicklaus, Tiger Woods) and football (George Best, Sir Matt Busby, Bryan Robson).
He has been awarded honorary doctorates by the universities of Salford, Manchester, London and Florence.
The Salford City Council have funded an archive and studio for Riley in a conservation area around the old Fire Station where he continues to work.
In 2009 cover artwork by Riley featured on a special limited edition CD by classical singer Jon Christosin aid of Christie Hospital.