He decided to become a full-time writer. He became a popular author with the publication, in 1925, of his first crime novel, "The Mystery of No.1", and with novels such as "Checkmate" (1930). Horler's work was influenced by other popular thriller writers such as Edgar Wallace and "Sapper". His main hero was "Tiger" Standish, a character similar to Sapper's Bulldog Drummond. Horler's work began to be commercially successful after being serialised in the "News of the World". By the 1930s, Horler's books had sold an estimated two million copies.