Julian Nagelsmann was born in Landsberg am Lech, Bavaria.

Nagelsmann played for FC Augsburg and 1860 Munich at youth level, and was the captain of Munich's U17 team.

Nagelsmann was part of the second team but made no appearances due to injuries. He returned to Augsburg for the 2007–08 season but injured his knee and meniscus again, leading to his decision to end his footballing career at age 20.