He was born in 1856, the second child and eldest son of George Baillie-Hamilton-Arden, 11th Earl of Haddington and Helen Katherine, daughter of Sir John Warrender, 5th baronet of Lochend by Frances Arden.

As such he was involved in the military arrangements for the Coronation of King Edward VII and Queen Alexandra in August 1902, and three days after the ceremony he was appointed a Member (4th class) of the Royal Victorian Order (MVO) on 12 August 1902, during a private audience with King Edward VII.

[4][5] He retired from the army in 1907, but remained in the Territorial Force as commanding officer of the Lothians and Border Horse, and served as His Majesty's Lieutenant of the County of Berwick from 1901 until he died.

[3] He thus did not inherit the title and possible election in the House of Lords (as a Scottish Representative Peer) as the Earl of Haddington; instead, it passed to his eldest son, George Baillie-Hamilton.

[3] His widow, Lady Binning, donated Fenton House in Hampstead, London to the National Trust on her death in 1952.