2009-10: Jon Gillies skated for the Neponsett River Rats Tier 1 Midget team and played in eight games at Salisbury School in Connecticut after transferring from North Yarmouth Academy. Gillies also attended USA Hockey's National Development Team Program's camp in April.
2010-11: Gillies joined the USHL's Indiana Ice and played 25 games in his first season. Gillies had a record of 15-6-2 as a backup to University of New Hampshire recruit Casey DeSmith and had a 2.82 goals against and .906 save percentage. He appeared in two of five playoff games for the Ice and was 0-1 with a 2.20 goals against and .932 save percentage. Gillies committed to attending Northeastern University in 2012-13. The Quebec Remparts selected Gillies in the ninth round (160th overall) of the 2011 QMJHL Draft.
2011-12: Gillies took over as the starter for the Ice after representing the USA in the 2011 Ivan Hlinka Tournament in the fall. In 53 games for the Ice he was 31-20 with three shutouts and had a 2.77 goals against and .915 save percentage. The Ice reached the Eastern Conference Finals after finishing second behind Green Bay in the regular season and in six playoff games Gillies was 3-3 with a 2.84 goals against and .911 save percentage. Gillies appeared in all four games at the Ivan Hlinka Tournament – starting three of them. He finished 3-1 including a shootout win and had an .892 save percentage. Gillies de-committed from Northeastern in March 2012 after it was announced that Huskies starter Chris Rawlings was returning for his senior season. Gillies was invited to the NHL Draft Combine and ranked sixth amongst North American goalies in Central Scouting's final rankings prior to the 2012 NHL Draft.
Gillies is a big goaltender who primarily plays a butterfly style. He doesn't sit back in his crease, instead challenging shooters and doing a good job of playing the angles. Gillies could stand to work on his rebound control, and as with any younger, lanky player, he'll need to become more comfortable in his body and improve his footwork. But in time, Gillies could end up as one of the top goaltenders from the 2012 class.
Gillies will play his freshman year at Providence College in the NCAA and the large goalie will be expected to start the majority of the Friars games this year as the team lost their starting and backup goaltenders to graduation. The third rounder should have at least four years of development at the NCAA level to improve his overall game.