As a paediatrician and pedagogue, a writer and children's rights advocate, Janusz Korczak (1878–1942) has had a large influence on thinking in Polish society. Most Poles still grow up with his children's stories, and Korczak's work culminated in Poland initiating and influencing the ten year process of writing the United Nations 1989 Convention on the Rights of the Child. Despite his cutting-edge ideas and his contribution to children's rights, only a few of Korczak's texts have been translated into English and his work has widely gone unrecognised. This paper aims to give English-speaking readers working in the children's rights sector an insight into Janusz Korczak's extraordinary life for children, into how his pedagogic thoughts and principles relate to newer ideas within the sociology of childhood and children's participation, and into his compelling children's rights advocacy and practice. His innovative ideas, preserved for future generations in his written work for children and adults, are still inspiring, prompting us to reflect on our own passion for children's rights and are helpful guides for our own practice.