In 1865, he was appointed High Sheriff of County Galway.[2] He became Baron Clonbrock in 1893 on the death of his father Robert Dillon, 3rd Baron Clonbrock and was appointed a Knight of the Order of St Patrick on 29 August 1900.[3]
He married Augusta Caroline Crofton, daughter of Edward Crofton, 2nd Baron Crofton of Mote and Lady Georgina Paget, on 18 July 1866 at Roscommon, County Roscommon, Ireland.[4] As a result of her marriage, Hon. Augusta Caroline Crofton was styled as Baroness Clonbrock on 4 December 1893.
The finding aid[5] of the collection related to the personal and political papers of the family of Dillon, Barons Clonbrock, Ahascragh (county Galway, c.1600-1960) was compiled by Stephen Ball, at the National Library of Ireland.