Throughout his career as a theatre director, Jerzy Grotowski encountered many different theatre cultures, which both collided with and were synthesized in his own practices. Confronted with Cold War mindsets and ideological constraints, Grotowski’s theatrical art reflects a kind of cosmopolitan spirit by embracing a common humanity. Analysing Grotowski’s biography alongside his theatrical innovations and theoretical thinking, this article aims to investigate the following three aspects of his theatrical cosmopolitanism: his encounters with different performance cultures in his theatrical concept of ‘poor theatre’, his advocacy of universal ethics in his representative theatrical production Akropolis, and his belief in world citizenship reflected in his concept of ‘art as vehicle’ from the later years of his career. As a pioneer in the contemporary experimental theatre and performance, Grotowski travelled, lived and worked all over the world, transcending the geographical and ideological divide between the Socialist and the Capitalist blocs during the Cold War. The adverse social conditions of the time did not hinder his creativity, but rather instigated his unmatched artistic talent and his cosmopolitan spirit, both of which are deeply interconnected and integrated.