2008-09: Dietz trained in the Catholic Central High School hockey academy and played 34 games with the Lethbridge Y's Titans in Alberta midget hockey – posting 4 assists with 62 PMs.
2009-10: Dietz, despite not being drafted in the WHL Bantam Draft, made his WHL with Saskatoon on Dec. 31 and played five games over the holidays. Dietz played three more games with the Blades in March. In eight games with Saskatoon, he scored 1 goal with 1 assist and had 4 PMs and was scoreless with 2 PMs in three playoff games. Dietz spent the bulk of the season playing midget hockey with the Lethbridge Y Hurricanes. In 33 games with the Hurricanes, he scored 9 goals with 15 assists and had 105 PMs.
2010-11: Saskatoon had a memorable regular season run in winning the WHL's East Division by 29 points and Dietz had a strong first full season for the Blades. In 68 regular season contests, Dietz scored 8 goals with 19 assists and was +17 with 66 PMs. Three of his eight goals came on the power play. In ten playoff contests, Dietz scored once and had 5 assists with 15 PMs. After defeating Prince Albert in a six-game first round series, the Blades were swept by eventual playoff champion Kootenay in the second round. Ranked 138th among North American skaters by Central Scouting, Dietz was selected by Montreal in the 5th round (138th overall) in the 2011 NHL Draft.
2011-12: After attending his first NHL Training Camp with the Montreal Canadiens, Darren Dietz was returned to his WHL Saskatoon Blades team where he was named an Alternate Captain for the 2011-12 season. The tough, physical defenseman played big minutes in the shutdown role while playing on both the power play and penalty killings units. Dietz improved on last season’s offensive numbers scoring 15 goals (five on the power play) along with 29 assists and a solid plus 7 while taking 118 PIMs (eight fighting majors) in all 72 WHL games. Dietz had a difficult first round loss in the 2012 WHL playoffs when his Saskatoon team was swept 4-0 by the Medicine Hat Tigers. The physical defenseman gave a wicked two-handed slash to the chest of the Tiger's star forward, Emerson Etem (ANA) after he scored on the Blades empty net to seal the win for Medicine Hat. The Blades' defender was lucky enough not to hurt Etem and he received only a one-game suspension. The offensive defenseman was never a factor on the score sheet in the series as he only contributed one assist in the first game and was a minus one rating in the three games.
A right handed shot, Dietz is not afraid to support the offense, and makes a smart first pass. He keeps active on the ice, willingly engaging the opposition with physical play. With prototypical size for an NHL backliner, Dietz is also willing to mix things up when the situation warrants and can make things difficult for opposing forwards.
Dietz will probably be returning to the WHL with the Saskatoon Blades for his third full year at the junior level where he will be expected to lead the defense corps with another Canadien's prospect, Dalton Thrower.