Born in Dumfries and a former pupil of Lockerbie Academy, Dunbar graduated in 2008 with an HNC from the Scottish Agricultural College at Auchincruive in Ayrshire.

[1] Dunbar has appeared for Glasgow at every age level from under-14 to under-18 and was Annan rugby club under-18 player of the year in both 2005 and 2006 and the following season.

[3] A Scottish Rugby Academy contracted player, Dunbar made his Glasgow Warriors debut in the 25–13 win against Ulster at Ravenhill in December 2009.

In January 2019, it was announced that Dunbar would spend the remainder of the season on loan at Newcastle Falcons and would then leave Warriors.

He scored a second-half brace of tries as Scotland posted their first win in the 2014 RBS 6 Nations Championship by 21–20 against Italy in Rome.