Remembered for his Gothic novels, satirical and political works, short stories, plays, and screenplays, he is perhaps most well known for The Green Hat (1924), Young Men in Love (1927), Lily Christine (1929), Man's Mortality (1933), and The Flying Dutchman (1939).
After briefly studying medicine at the University of Edinburgh, he published his first work, The London Venture, in 1920.
Born Dikran Kouyoumdjian to Armenian parents, he spent his youth in Bulgaria and England and grew up with older siblings named Ahavni, Roupen, Takvor, and Krikor. His marriage to Countess Atalanta Mercati produced children named Michael and Venetia.
In 1956, Arlen's thriller The Gentleman from America was adapted into an episode of Alfred Hitchcock Presents.