2010-11: Blake Siebenaler played forward for the Carroll Chargers high school team in Indiana and was the team's leading scorer as a freshman. He scored 20 goals with 12 assists in 17 regular season games. Siebenaler scored 3 goals with 3 assists in four state tournament games and Carroll defeated Columbus to capture the Indiana 4A state championship.
2011-12: Siebenaler skated for the Cleveland Barons U16 midget and participated in USA Hockey's Select 16 Festival in July 2012. He scored 5 goals with 7 assists and had 6 penalty minutes in 40 games as a defenseman for the Barons. Siebenaler was selected by Indiana in the second round (23rd overall) of the 2012 USHL Futures Draft and was selected by Niagara in the 15th round (302nd overall) in the OHL Priority Selection.
2012-13: Siebenaler played for the first-place USA U17 team at the Five Nations Tournament in the Czech Republic in August and appeared in 11 USHL games with Indiana; spending most of the season playing for the Belle Tire U16 team in Michigan. He had no points nor penalty minutes in four games with the USA. In 11 games for the Ice he was -11 with 1 goal, 2 assists and 8 penalty minutes. Siebenaler played 50 games with the Belle Tire U16 team. He scored 9 goals with 9 assists and had 22 penalty minutes in 39 regular season games and scored 4 goals with 3 assists in 11 playoff contests. He capped the season by participating in USA Hockey's Select 17 Development Camp in July 2013.
2013-14: Siebenaler signed with the OHL's Niagara Ice Dogs in August 2013; foregoing college hockey. One of three playmaking defensemen for the Ice Dogs, he scored 2 goals with 20 assists in his first 53 games and was -18 with 22 penalty minutes on a Niagara team that was fighting for a playoff spot. Siebenaler was ranked 47th amongst North American skaters in Central Scouting's mid-season rankings prior to the 2014 NHL Draft.