Career
Karner started his career in 2005 in Red Bulletin Salzburg. In 2010 he moved to SV Ried, but in the same year he was loaned to SV Grödig. In June 2011 he came back to SV Ried.
In 2013 he signed one-year deal with SV Grödig.
On 6 July 2015, Karner signed two-year deal with Levski Sofia in Bulgaria. He made his Levski debut against Botev Plovdiv on 18 July, starting as a centre back in a 1–1 league draw.
