Jonny Gray became the 1050th Scotland cap when he was introduced for his brother Richie in the second-half of Scotland's viagogo Autumn Test against South Africa in November 2013. Jonny was a Scottish Rugby Elite Development player attached to Glasgow Warriors before he signed a full-time contract with the club. On the 2014 summer tour, Gray enjoyed his first start for Scotland in the 21-19 win against Argentina in Cordoba.
He joined the Warriors in the summer of 2012 on the back of standout displays for Hamilton and Scotland under-20. He started his first game for the national under-20 side at age just 17 and was selected as Scotland under-20 captain for the 2013 RBS 6 Nations. He has been capped on 14 occasions for Scotland under-20.
The younger brother of Scotland second row, Richie Gray, Jonny was named as one of the recipients of the 2012 John Macphail Scholarship and spent three months developing his rugby in New Zealand. He made his full professional debut as a substitute against Edinburgh Rugby in December 2012.