Smile, 20, came up through the ranks in Oxford United before being spotted by a Fulham scout.
In 2013 he left the U's and finished his youth education at Craven Cottage.
During his development the 5`6” midfielder managed to break into the Cottagers under-23 team where he eventually became captain.
Oxford-born Smile, who is regarded as a tough-tackling midfielder with an eye for a pass, has recently been back at Oxford United on trial.
Chippenham manager Mark Collier said: "Josh has been training with us for a couple of weeks and has been impressive. He is quick, bright and can play in several positions, with Jake Andrews returning to Bristol City it was important to add to the squad, it's vital we keep a competitive squad in keeping with quality and numbers".