He reached his career-high singles ranking of world No.

[1] Kern made his ATP World Tour debut in 2011, when he was given a wild card into the main draw of the 2011 MercedesCup.

There, he lost in the first round to Fabio Fognini in straight sets.

In 2012, Kern was again awarded a wild card into the main draw of the MercedesCup, where he lost to Thomaz Bellucci in the first round.

In 2013, he received a wild card into the MercedesCup for the third consecutive time, losing to German qualifier Nils Langer 6–3, 4–6, 3–6 in the first round.