Hubbard published the first science fiction novel Danger Zone in 1938. In the next ten years, he was an active "all-round" writer: his works were published under his real name, or under the pseudonyms of Kurt von Rechin, Renee Laffler, Frederic engelhardt and others. Although there is no clear boundary, Hubbard seems to only publish fantasy novel with his real name in Unknown or other magazines, and publish science fiction with von Rechin and Raffel in ASF magazine.

His most famous novel, The Last Faint, tells that after years of war, the world was riddled with holes, and a young officer became the dictator of Scotland, leading all Scots to resist the declining United States. The Slave of Sleep and its sequel Master of Sleep are also his famous fantasy novels, and the story takes place in the dark Arab world.

His most influential fantasy novels are Fear, Space Typist and The Final Adventure. The Space Typist was first published in Unknown magazine (1940), The Last Adventure was published in 1949, Back to Tomorrow was published in ASF (1950), and Dr. Matthew Serra was published under the pseudonym of Renee Raffler. His other series of works, Conquering Space, were published in Startup Fiction magazine, including No Navigation, Serious Failure, Incredible Destination, Unwilling Hero, Beyond the Black Nebula, King of the Universe and The Last Admiral. Under the pseudonym Kurt von Rechin, the series Cat in kilkenny: The Idealist (1940) and Cat in kilkenny (1940) were published in ASF. In addition, rebels (194 1) and rebels (1942) are also more influential.

Battlefield earth, Earth Mission Series, Fear, Typewriter in aky, Slave of Sleep & Master of Sleep, The Last Faint, etc.

Hubbard's sci-fi masterpiece Killing Fields on Earth has distributed 4 million copies in 12 languages all over the world. Publishers Weekly commented on this novel: "It is a master of suspense, pity, fighting, humor and deception." The book tells a story that happened in 3000 AD with epic solemnity: the earth has been ruled by the alien Sekulo 1000, and Johnny Goodbo Taylor is one of the few surviving earthlings who escaped. He decided to venture away from his declining tribe in the Rocky Mountains. With the help of Scots and China people, Johnny unites the earth people to challenge the evil forces that are destroying the earth. According to an article in Publisher's Weekly on March 25th last year, Killing the Earth will be put on the screen by MGM Hollywood, and john Travolta, the star of Broken Arrow, will continue to play the leading role in the film.