The name Mylie means Smiley and is of American origin. Mylie is a name that's been used primarily by parents who are considering baby names for girls.
The name Miley grew in popularity after the success of teen actress and singer, Miley Cyrus. Although Miley's birth name was Destiny Hope, she was nicknamed "Smiley Miley" by her parents as a baby. Cyrus legally changed her name to Miley in 2008.