Saint Agnes of Prague, also known as Agnes, was born on January 20, 1205, in Prague as the youngest daughter of Czech King Přemysl I. Otakar and Queen Constance. Her early life was marked by unusual circumstances as she was engaged at the tender age of three to Boleslav, son of the Silesian Duke Henry the Bearded. After Boleslav's death, Agnes returned to Czechia, only to be engaged again, this time to the son of Holy Roman Emperor Frederick II. By the time she grew up, it became clear that her true calling lay not in a royal marriage but in a spiritual life.

In her formative years, Agnes was educated in a Cistercian convent in Silesia, where she developed a strong character and a deep sense of spiritual commitment. The pressures of political alliances and royal expectations did not deter her from pursuing a life dedicated to faith and the teachings of Christ. Eventually, she corresponded with Saint Clare, a significant figure in the development of the Poor Clares, reflecting her commitment to a life of humility and service.