Born in Girard, Illinois, Florence Finch Kelly (née Finch) was the youngest child of two daughters and six sons of James Gardner Finch and Mary Ann Finch (née Purdum). Her father was a farmer in Illinois and Kansas, where the family moved by covered wagon. Charles Sumner Finch, one of her brothers, became a newspaper publisher in Kansas. She married in Boston the newspaper publisher Allen P. Kelly on 9 December 1884; they had a son, Morton, who died in childhood and another son, Sherwin Kelly, who became a noted geophysicist.
Finch contributed many articles to the Boston Globe and the anarchist periodical Liberty. In 1906 she visited New Zealand and Australia to study the effects of social and economic legislation in those countries and wrote numerous magazine articles related to the social and economic changes. She worked on the staff of the New York Times as a book reviewer from 1906 to the mid 1930s. In addition to seven novels and numerous short stories and magazine articles on literary, artistic, and economic subjects, Florence Finch Kelly wrote an autobiography Flowing Stream: The Story of Fifty-six Years in American Newspaper Life (1939). She died in New Hartford, Connecticut in 1939.