Gray started playing rugby at Cambuslang RFC where he progressed from the mini section (at 7 years old) through to first XV regular at the age of 16.

At just 21 years of age, Gray was named captain of Glasgow Warriors in November 2015, taking over from recently retired mentor Alastair Kellock.

[6] He became a co-captain with Henry Pyrgos for the 2016-17 season but following the arrival of Dave Rennie as Warriors Head Coach the club has reverted to a sole captaincy.

[9] On 4 July 2024, Gray would sign for French side Bordeaux, after his early departure from Exeter, in the Top 14 competition from the 2024-25 season.

[citation needed] In 2013 Gray was included in a 41-man squad for Scotland's senior side in the 2013 end-of-year rugby union tests.