2009-10: Cole Ully played for the Calgary Bronks bantam AAA team. He had 64 points in 32 games for the Bronks and was selected by Kamloops in the second round (30th overall) of the 2010 WHL Bantam Draft.
2010-11: Ully made his WHL debut, appearing in a February game with Kamloops three days after his 16th birthday, and was the second-leading scorer for the Calgary Flames midget AAA team. Ully had an assist in his only game with the Blazers. He scored 17 goals with 17 assists in 32 games for the Flames and had 20 penalty minutes. He was scoreless in two playoff games. Ully played for Team Alberta in the Canada Winter Games. He scored 3 goals with 2 assists and 26 penalty minutes in six games as Team Alberta won a bronze medal.
2011-12:Ully skated in 55 of 72 games for Kamloops in his first WHL season. He scored 9 goals with 11 assists and was +7 with 2 penalty minutes playing for one of the league's top teams. The Blazers finished first in the B.C. Division and reached the second round in the playoffs. Ully played in 6 of 11 playoff games, scoring 1 goal with 1 assist, and was +1 with 2 penalty minutes.
2012-13: Ully was Kamloops' fifth-leading scorer in his second season. He played 62 games for the Blazers, missing all but two games in December after suffering a concussion. He scored 22 goals with 28 assists and was +27 with 37 penalty minutes. Kamloops finished second in the B.C. Division before advancing to the West Conference finals. Ully scored 1 goal with 7 assists, skating in all 15 playoff games, and was +2 with 4 penalty minutes. He was ranked 92nd amongst North American skaters in Central Scouting's final rankings and was selected by Dallas in the fifth round (131st overall) of the 2013 NHL Draft.