Born on 18 December 1786, he was the son of Alexander Leslie-Melville, 7th Earl of Leven, and Jane née Thornton. He was for many years a partner in the banking house of Messrs. Williams, Deacon, and Co. of Birchin Lane. He succeeded his brother as 9th Earl of Leven and 8th Earl of Melville on 8 October 1860, by when he had more than passed the age of 70. He was elected one of the 16 Representative Peers for Scotland in 1865, and was rechosen in 1868, and again in 1874. He was also a Deputy Lieutenant for Surrey.

He married, firstly, Harriet Thornton, daughter of Samuel Thornton M.P., on 15 September 1812. He married, secondly, Sophia Thornton, daughter of Henry Thornton M.P., on 23 April 1834. Lord Leven had, by his two marriages, a family of 14 children, of whom 7 survived him.

Lord Leven died on 9 September 1876, aged 89.