O'Shaughnessy was born in London to a family of Irish descent. In 1861, at age 17, he was employed
as a copyist at the British Museum but, in 1863, became a herpetologist in the department of
ichthyology where he remained for the remainder of his life.
He published a few volumes of poetry starting with Epic of Women, 1870, Lays of France, 1872,
which revealed his attraction to French poetry, and Music and Moonlight, in 1874. Songs of a Worker
was published posthumously in 1881. He formed friendships with Dante Gabriel Rossetti and other
poets and artists marrying Eleanor Marston, sister to the poet Philip Bourke Marston in 1873.
They jointly wrote a book of children's stories entitled Toyland published in 1875; but their two
children died in infancy. Eleanor died in 1879.
O'Shaughnessy died in 1881 from a chill that proved fatal to his weak constitution.
His works are considered as occupying a mellifluous tone without rising to their fullest potential.
His reputation rests on a few melodic poems, in particular, his Ode, that was memorably set by
Sir Edward Elgar as The Music Makers.