Mason began his football career at the youth academy of Tottenham Hotspur, before going on loan to several clubs including Yeovil Town, Doncaster Rovers, Millwall, Lorient, and Swindon Town. He eventually made his breakthrough into the first team of Tottenham Hotspur in 2014 and went on to make 70 appearances for the club before retiring due to a serious head injury in February 2018.