He has been capped at youth international level by Germany and Austria. Leitner made his professional debut playing for his childhood club 1860 München on 14 August 2010, when he came on as a substitute for Aleksandar Ignjovski in a DFB-Pokal match against South Carolina Verl. In January 2011, he was transferred to Borussia Dortmund and subsequently joined Augsburg on loan until the end of the 2010-2011 season.
In summer 2011, Leitner joined Borussia Dortmund and played 22 games in his first season.
Because of the impressive competition at the playmaker position, he played only four times as a starter in the 2011/12 season. In those 22 games, he scored two assists.
In the 2012/13 season, Leitner got some more game time (30 games) after the departure of Shinji Kagawa but because of the impressive performances of Mario Götze, he played as a starter only at ten times. He had three assists with no goals scored.
On 1 July 2013 Moritz Leitner joined VfB Stuttgart on loan until June 2015.
He made his Stuttgart debut in their first game of the Bundesliga season. On 1 February 2014, Leitner scored his first Bundesliga goal in Stuttgart"s 2–1 defeat at Bayer Leverkusen.