The highly-rated attacker joined Celtic on transfer deadline day – February 2, 2015 – from Derry City following a successful trial period at the club, putting pen to paper on a four-and-a-half year contract.
After rising through the ranks at the Candystripes, Duffy made his first-team bow in the summer of 2012 and bagged his first goal the subsequent season against Shelbourne.
The 20-year-old rose to prominence during a stellar 2014 season in which he found the net 16 times in all competitions for his hometown club.
His fantastic form earned him a call-up to Northern Ireland Under-21s, with Duffy collecting his first cap in September 2015 against Serbia.