He was the eldest son of William Mills, a director of the Honourable East India Company, and the elder brother of Sir Charles Mills, 1st Baronet.
[2] Mills was educated at Harrow and Christ Church, Oxford, matriculating on 22 October 1807.
Mills served with the regiment during the Peninsular War and in Holland.
[8] On 28 July 1835, Mills married Sarah Charlotte Micklethwait (1813–1869), a daughter of Nathaniel Micklethwait and Lady Charlotte Marianne Harriet Rous (daughter of the 1st Earl of Stradbroke).
[2] Through his second son, he was a grandfather of John Mills, MP for New Forest and Christchurch.