He was educated in the United States and in Dublin, at Sandford Park School, a non-denominational school selected by his mother in the face of strong criticism from her Catholic and nationalist friends. His cousin, the diplomat, writer and politician Conor Cruise O'Brien, was a pupil there at the same time.
In 1935 Sheehy-Skeffington married Andrée Denis, a French graduate of the Sorbonne, with whom he had two sons and one daughter. She later wrote a biography of her husband, Skeff: A Life of Owen Sheehy Skeffington, 1909-1970. They resided at Hazelbrook Cottage, Rathfarnham, Dublin.
In the late 1950s the memorialist Peter Tyrrell began a long-lasting correspondence with him. Sheehy-Skeffington encouraged Tyrrell to write his autobiography, which was published posthumously and helped to expose the brutal conditions in Irish Industrial schools, and in Letterfrack in particular. After Tyrrell committed suicide in 1967 the only clue to his identity was a card addressed to Sheehy-Skeffington.
Since 1973 Trinity College, Dublin, has offered the Owen Sheehy-Skeffington Memorial Award, a bursary worth 1,500 euros awarded annually, as a maintenance grant or as a travel award in alternate years. The criteria for the award include a combination of academic promise and financial need. The maintenance grant is available to senior freshmen or junior sophisters studying French at Trinity College, while the travelling scholarship may be granted to any student attending a centre of higher education in Ireland.