Cassidy was admitted to hospital after suffering organ failure on November 18, 2017.
Although his cause of death is still to be confirmed, it is believed he suffered multiple organ failure.
After leaving The Partridge Family, Cassidy became a solo superstar, selling out concerts across the world – including six shows at Wembley Stadium over one weekend in 1973.
Such was the hysteria that the heartthrob generated that the media coined the phrase "Cassidymania".
David Cassidy was born in New York City on April 12 1950, the son of singer and stage star Jack Cassidy and actress Evelyn Ward.
He made his stage debut in 1969 while still a teenager, before signing with Universal Studios and moving to Los Angeles.