Autobiography definition is - the biography of a person narrated by himself or herself. Biography is a detailed account of a person's life written by someone else, while autobiography is written by the subject themselves. Many scholars regard the Confessions (c. 398) by Augustine of Hippo (354–430) as the first autobiography. See more. Autobiography definition, a history of a person's life written or told by that person. The person writes about everything he went through in his life. As per the autobiography definition, it is a story that is written by the same person on whom the story is based. How to use autobiography in a sentence. An autobiography is an account of a person's life written or otherwise recorded by that person. Biography can be written with (authorized) or without permission (unauthorized) from the person/heir's concerned. Adjective: autobiographical. The definition of Autobiography is based on one’s life story.