Career
He is the younger brother of Nottingham Forest defender Matthew Mills and can play at either left back or left midfield. Southampton
He made his Southampton first team debut as substitute in a League Cup match against Birmingham City on 26 August 2008. He made his league debut at home against Barnsley on 20 September 2008.
On 23 February 2009, he joined Scunthorpe United on an emergency loan for one month.
On 24 March, the loan was extended to the end of the 2008-2009 season. He signed a new three-year contract in August 2009 after some good pre-season performances, featuring sporadically during the 2009-2010 season.
However, Mills did play in Southampton"s victorious Football League Trophy final against Carlisle United. He joined Doncaster Rovers on a one-month emergency loan deal on 19 October 2010, making his debut the same day in a 3–2 defeat by Derby County.
This loan deal was then extended to 19 January 2011.
Mills was injured in Doncaster"s 3–0 defeat to Reading on 15 January 2011 and this may have been his last action for Doncaster. In July 2011, he joined Preston North End F.C. on trial. Mills scored his first professional goal for Doncaster in a 3–0 victory over former loan club Scunthorpe United.
On 31 January 2011, the loan deal was extended until the end of the season.
Reading
On 22 August 2011, he joined Reading for an undisclosed fee, signing a one-year contract with the option of another year. He made his first start for the Royals in a 2–1 defeat by Charlton Athletic, in the League Cup first round on 23 August 2011, coming off the bench for Ian Harte in the 62nd minute.
Mills signed a contract extension on 8 February 2012 keeping him at Reading until the end of the 2014 season. Burnley
On 17 July 2012, Mills joined Burnley on a season long loan after falling down the pecking order at Reading.
He went on to make 10 league appearances during the 2012-2013 season, before joining Burnley permanently in the summer of 2013, signing a two-year contract.
On 16 August 2013, he joined League One side Oldham Athletic on a one-month loan deal. On 31 January 2014, Mills joined Shrewsbury Town on loan for the remainder of the 2013-2014 season. Oldham Athletic
On 4 June 2014, Mills signed for Oldham Athletic where he had spent a loan spell the previous season.
He signed a two-year contract with the option of a third and was the Latics first summer signing.
Manager Lee Johnson said of the signing "lieutenant"s a great signing. He"s young, hungry and got a lot of potential.
We"ll give him an identity and a bit of love and I feel he can be a really good player for us.".