2011-12: Dallas Valentine played for the Red Deer IROC Chiefs midget minor AAA team in Alberta.
2012-13: Valentine attended Moose Jaw's camp as a 16-year-old and appeared in 13 WHL games — skating with the midget AAA Leduc Oil Kings most of the year and suffering a hip injury that kept him out of action for a good portion of the season. He made his WHL debut in mid-January and had 1 assist; finishing 1- with 4 penalty minutes in limited action with the Warriors. In 26 games in the Alberta Midget Hockey League with Leduc he scored 1 goal with 1 assist and was -1 with 4 penalty minutes.
2013-14: Valentine stepped into a key role for Moose Jaw in his first full season with the Warriors. In 69 games he scored 3 goals with 11 assists and was -28 with 44 penalty minutes. Moose Jaw had the WHL's fourth-worst record and missed the playoffs after finishing fourth in the East Division. Valentine was ranked 105th in Central Scouting's final rankings prior to the 2014 NHL Draft.