He is chiefly remembered as an author of numerous works of fiction and nonfiction for children, much of it on historical or patriotic subjects.

As an adult he lived in Philadelphia and New York City until removing to Somerville, Massachusetts, his mother's home town, in 1887.

Brooks started writing fiction, poetry and plays for children in 1879, his work appearing in St. Nicholas, Wide Awake, Harper's Young People, Golden Days, and The Independent.

Brooks also wrote some material for adult audiences, including one of his earliest books, a biography of his own father.

Brooks' works were dismissed by some critics as "machine-made," but proved enduringly popular, some continuing to be reprinted many years after his death.