He was the first son of the previous head of the family of Jorge Torlades O'Neill II and wife Maria Isabel Mazziotti da Costa Cordeiro Fernandes. He was also the Representative of the title of Viscount of Santa Mónica, in Portugal.
He married in Lisbon, Santos-o-Velho, on 14 February 1906 Dona Júlia Margarida Catarina de Serpa Pimentel de Sousa Coutinho, daughter of Dom Fernando de Serpa Leitão de Mansilha Pimentel and wife Dona Maria Ana Vitória de Sousa Coutinho, and had four children:
Maria Ana do Carmo O'Neill, married Lisbon, Encarnação, 3 January 1929 her co-brother-in-law Dr. Dom João José de Melo, son of Dom António Vasco de Melo da Silva César de Menezes, 10th Count of Sabugosa and 12th Count of São Lourenço and representative of the title of Marquess of Sabugosa, and wife Berta Munró dos Anjos, and had three children
Maria Isabel de Jesus O'Neill, married Lisbon, Encarnação, 11 April 1929 her co-brother-in-law Dom António Vasco José de Melo da Silva César de Menezes, 4th Marquess and 11th Count of Sabugosa and 13th Count of São Lourenço, son of Dom António Vasco de Melo da Silva César de Menezes, 10th Count of Sabugosa and 12th Count of São Lourenço and representative of the title of Marquess of Sabugosa, and wife Berta Munró dos Anjos, and had five children
Fernando Hugo Maria O'Neill, Civil Engineer from the Instituto Superior Técnico of the University of Lisbon, married Lisbon, Santos-o-Velho, 6 October 1947 Maria Lívia Rita da Graça de Sá Pais do Amaral Franco, daughter of Dr. Frederico Gaspar Schindler Franco Castelo-Branco and wife Maria Rita de Sá Pais do Amaral, and had four children:
* Rita Maria Franco O'Neill, After receiving a diploma from the Instituto Superior de Línguas e Administração of the University of Lisbon, married Lisbon, Prazeres, 27 March 1971 Dom Sebastião Maria de Sá Coutinho de Lancastre, son of Dom Sebastião de Oliveira e Almeida Calheiros de Lancastre and wife Maria Angelina de Sá Coutinho Rebelo Sotomaior, without issue
* João Hugo Maria Franco O'Neill, Agricultural Engineer by the Instituto Superior de Agronomia, married Oeiras, Caxias, 29 September 1975 Maria da Graça de Castelo-Branco Schedel, daughter of João Ferrão de Castelo-Branco Schedel and wife Dona Maria Isabel da Visitação de Siqueira de Castelo-Branco, and had two children:
** Vera Schedel O'Neill, married Lisbon, Prazeres, 13 December 1997 Manuel de Atouguia Belford Correia da Silva, son of Pedro de Barros Belford Correia da Silva and first wife Margarida Maria de Castro de Atouguia, and had one son
* Maria Ana Franco O'Neill, Licentiate in Mathematics from the University of Lisbon, married Lisbon, Prazeres, 26 October 1973 as his first wife Dr. Dom Manuel José de Gouveia Portela de Herédia, Licentiate in Law from the University of Lisbon, Lawyer, son of DomJosé de Freitas Branco de Herédia and first wife Maria do Carmo de Gouveia Portela, and had three children
