Róbert Grondžel was born in Slovakia in 1977. He began his music education with Jozef Bikár, who is the principal double bass player at the State Philharmonic Orchestra of Košice. Later, he enrolled at the Hochschule für Künste in Bremen, Germany, where he studied under Stefan Adelmann, the principal double bass of the Bamberg Symphony Orchestra.

Róbert gained his first orchestral experience in 2001 as part of the Orchesterakademie at the Theater Münster. In 2002, he made his debut with the Deutsche Oper Berlin. The following year, he was appointed second assistant principal double bass at the Museum Orchester Frankfurt, and in 2005, he received a permanent position as assistant principal double bass with the Danish National Opera.

Since 2008, Róbert has served as the principal double bass with the Beethoven Orchestra Bonn. This orchestra's regular activities include opera, chamber music, educational concerts, as well as musicals and cross-genre performances, in addition to the standard repertoire.