Kralj was born in Zagreb to a Serb family from Banija.

During World War II his family fled to Syrmia, where he grew up.

He graduated from a gymnasium in Novi Sad and studied acting at the University of Arts in Belgrade.

Kralj appeared on stage about 3,000 times, and starred in over 200 films, TV series and TV films, gaining huge popularity as one of the most recognizable Serbian actors.

In 2005, he played the lead role in first Serbian science fiction television series The Collector.