Witmyer started his junior career in 2008 – 2009 with the New York Applecore where was top five in EJHL rookies in points with 33 in 41 games. He registered 13 goals and 20 assist. In 2009 – 2010, Witmyer played with the Philadelphia Revolution and the Springfield Pics both in the EJHL. He tallied with 5 goals and 11 assist for 16 points in 24 games. In his last year of juniors, Witmyer played in the EJHL for the Philadelphia Revolution and dressed in 37 games. He scored 4 goals and added 24 assist for 28 points. He appeared in 101 career games and had 77 career points. He was select to the EJHL All-Star team during his first year of juniors in 2008.