Riley's boyhood experience as an itinerant sign painter, entertainer, and assistant to patent-medicine vendors gave him the opportunity to compose songs and dramatic skits, to gain skill as an actor, and to come into intimate touch with the rural populace of Indiana. His reputation was gained first by a series of poems in Hoosier dialect ostensibly written by a farmer, Benj. F. Johnson, of Boone, contributed to the Indianapolis Daily Journal and later published as “The Old Swimmin'-Hole” and 'Leven More Poems (1883). Riley was briefly local editor of the Anderson (Ind.) Democrat, but his later life was spent in Indianapolis.

Among Riley's numerous volumes of verse are Pipes o' Pan at Zekesbury (1888), Old-Fashioned Roses (1888), The Flying Islands of the Night (1891), A Child-World (1896), and Home Folks (1900). His best-known poems included “When the Frost Is on the Punkin,” “Little Orphant Annie,” “The Raggedy Man,” and “An Old Sweetheart of Mine.” His poems were collected in Complete Works, 10 vol. (1916).