[2][3] Starkl's strong start in Hütteldorf led to a quick promotion from the youth ranks to the reserve team.

Reserve team coach Zoran Barisic handed him his debut on 9 August 2011 in a 2–1 win against SC Neusiedl am See, where he played 77 minutes.

Under coach Peter Schöttel, he made his Bundesliga debut in November 2012 as a second-half substitute against Sturm Graz, where he assisted Guido Burgstaller in a 2–1 loss.

[7] Starkl signed with Austrian Second Division club SKU Amstetten ahead of the 2022–23 season, penning a contract until June 2024.

[11][12] In July 2024, Starkl returned to his childhood club, Kremser SC, which competed in the Austrian Regionalliga East.