Elia Wilkinson was the daughter of Frederick and Amanda (Cahill) Wilkinson. She was born in Kalamazoo, Michigan, but moved with her family to Chicago when she was young. She stopped attending school when she was fourteen, but kept up a reading habit. In 1883 she married Robert Burns Peattie, a Chicago journalist. She began writing short stories for newspapers, and became a reporter with the Chicago Tribune and subsequently the Chicago Daily News. In 1889 she moved to Omaha, becoming chief editorial writer on the Omaha World-Herald. She wrote for magazines including Century, Lippincott's Magazine, Cosmopolitan Magazine, St. Nicholas, Wide Awake, The American, America, Harper's Weekly, and San Francisco Argonaut.
In 1888 she was commissioned by Chicago publishers to write a young people's history of the United States, and wrote the seven-hundred page The Story of America in four months. Her novel The Judge won a $900 prize from the Detroit Free Press in 1889, and was subsequently published in book form. Later in 1889 the Northern Pacific Railroad employed her to visit and report on Alaska: A Trip through Wonderland became a popular guide-book. With Scrip and Staff (1891) was a story of the children's crusade.
Peattie was a member of the Eagle's Nest Art Colony in Ogle County, Illinois.
Peattie subsequently returned to Chicago and became literary editor of the Chicago Tribune. One of her sons was the famed botanist, naturalist and author Donald Culross Peattie (21 June 1898 - 16 November 1964).