Called the "Apostle of the North", Hyacinth was the son of Eustachius Koński of the noble family of Odrowąż.

A near relative of Ceslaus, he made his studies in notable cities: Kraków, Prague, and Bologna, and at the latter place merited the title of Doctor of Law and Divinity.

On his return to Poland he was given a prebend at Sandomierz, a medieval centre of administration in the south-eastern part of the country.

[2]While in Rome, he witnessed a miracle performed by Dominic of Osma, and became a Dominican friar, along with Ceslaus and two attendants of the Bishop of Kraków, Herman and Henry.

In 1219 Pope Honorius III invited Dominic and his followers to take up residence at the ancient Roman basilica of Santa Sabina, which they did by early 1220.

[3] Tradition holds that he also evangelized throughout Sweden, Norway, Denmark, Prussia, Scotland, Russia, Turkey, and Greece.

As the friars prepared to flee the invading forces, Hyacinth went to save the ciborium containing the Eucharist from the tabernacle in the monastery's chapel, when he heard the voice of Mary, asking him to take her, too.

Kraków's annual Pierogi Festival is held on St. Hyacinth's feast day, and the winner receives a statuette of him.