Brought up an Irish Catholic, he was educated locally in Roscommon, and at St Nathy's College in Ballaghadereen.
[2] Favoured by Cardinal Cullen, his status as a ultramontanist helped him to obtain the position of bishopric of Elphin.
[3] During Gillhooly's time in Elphin, he developed many churches, including the redevelopment of Sligo Cathedral.
He was a highly organised and disciplined correspondent and his vast archive has been preserved allowing a better study of his episcopacy.
He is regarded as a perfect example of a Cullenite bishop in post-Famine Ireland, determined to implement the so-called 'devotional revolution' to his largely rural diocese.