He was twice elected to the Parliament of the United Kingdom as a Scottish representative peer, serving once from 14 January 1833 to 29 December 1834 and then again from 8 September 1847 to 23 April 1859.
He succeeded his father as Lord Elphinstone in May 1813, and entered the army in 1826 as a cornet in the Royal Horse Guards.
The king made him a Knight Grand Cross of the Royal Guelphic Order in 1836, in which year he was sworn of the privy council.
Elphinstone checked the rising at a few places in his presidency, and put down the insurrection of the Rajah of Sholapur.
He died unmarried in King Street, St. James's, London, on 19 July 1860, when his peerage of the United Kingdom became extinct.