Joseph Nathan Mills is an English footballer who plays for Southampton.

Born in Swindon, he is the younger brother of Leicester City defender Matthew Mills. He can play at either left-back or left midfield. 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. n 24 March, the loan was extended to the end of the 2008–09 season.

He signed a new three-year contract in August 2009 after some good pre-season performances, featuring sporadically during the 2009–10 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.