He contributed substantially to "Envoy" (he was "honorary editor" for the special number featuring James Joyce) and formed part of the "Envoy" / McDaid's pub circle of artistic and literary figures that included Patrick Kavanagh, Anthony Cronin, Brendan Behan, John Jordan, Pearse Hutchinson, J.P. Donleavy and artist Desmond MacNamara who, at the author's request, created the book cover for the first edition of "The Dalkey Archive". O'Brien also contributed to "The Bell". He also wrote a column titled "Bones of Contention" for the "Nationalist and Leinster Times" under the pseudonym George Knowall; those were collected in the volume "Myles Away From Dublin".