Born in Swindon, England, Mills started his football career at Southampton, alongside with his brother, Matthew and progressed through the academy and the reserve for two seasons before being promoted to the first team ahead of the 2008--09 season.
Born in Swindon, England, Mills started his football career at Aston Villa's academy before opting to move to Southampton. At Southampton, alongside his brother Matthew, he progressed through the academy and reserve sides before being promoted to the first team ahead of the 2008--09 season.