He left Maynooth after ordination for the Diocese of Clonfert[2] in 1895 and was appointed as a Roman Catholic priest to Loughrea, County Galway between 1896 and 1904.

He was an enthusiastic advocate of the Gaelic League and the Irish Cooperative Association, and promoted his views in articles and lectures.

He was in charge of decorating St Brendan's Cathedral, Loughrea in 1901, the financing provided by O'Donovan's close friend Edward Martyn.

[citation needed] He moved to London but failing to find work as a priest, he left the Catholic priesthood in May 1908.

[citation needed] In her novel The Towers of Trebizond Macaulay featured a woman character (Laurie) torn between her attraction to Christianity and her adulterous love for a married man; this is considered to reflect the author's relationship with O'Donovan.