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.
[6] He was re-elected in 1832, and held the seat until he stood down at the 1835 general election.
[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.