In 1871 Jones, the widow of an iron-moulder who had died in 1867 in an epidemic in Memphis, Tennessee, lost all her possessions in the great Chicago fire. She turned to the Knights of Labor for assistance, attracted by their campaign for improved working conditions. By 1890 she had herself become a highly visible figure in the American labour movement. She traveled across the country, both organizing for the United Mine Workers and orating on her own, supporting strikes, and galvanizing public support for labour with her slogan, “Join the union, boys.”

Jones was also an active proponent of legislation to prohibit child labour. She was one of the founders of the Social Democratic Party in 1898 and of the Industrial Workers of the World in 1905. Her Autobiography of Mother Jones was published in 1925.