Bartholomew was born at Riverston, County Meath, eldest son of Sir James Dillon and his wife Elizabeth Bathe.
[3] His father's family was Old English and descended from Sir Henry Dillon who came to Ireland with Prince John in 1185.
[14] Bartholomew and Elizabeth had a son: —and two daughters: Dillon's younger brother Robert founded the branch of the family that would later hold the title Earl of Roscommon.
On 15 January 1533 he was made Lord Chief Justice of the King's Bench for Ireland[19] but died suddenly soon after.
[20] According to Elrington Ball, at a time when the Irish ruling class were deeply split between supporters (the so-called Geraldines) and opponents of the 9th Earl of Kildare, Dillon was one of the most committed Geraldines, and spent much of his time in England defending the Earl of Kildare's interests.