In 1241, when the kingdom of Hungary was largely overrun by Tatars, King Bela IV and his Queen Maria Laskarina (daughter of Theodore I, Nicaean emperor of the Romans), who had withdrawn to a fortified city in Dalmatia, promised their next child to God should the kingdom be spared further devastation.
The Tatars withdrew and in the following year Margaret was born. Her parents kept their vow and at the age of three or four Margaret entered the Dominican convent at Veszprém. At the age of twelve she entered a new Dominican convent her father had had built for her on an island in the Danube near Buda. Here Margaret passed all her life, which was consecrated to contemplation and penance, and ultimately made her profession before Bl. Humbert of Romans, Master General of her order.
According to legend, Margaret appears to have taken solemn vows when she was eighteen and strenuously opposed the plans of her father, who for political reasons wished her to marry King Ottokar II of Bohemia. She chastised herself from early childhood, wore an iron girdle, hair-shirts, and shoes spiked with nails. She later also would perform the dirtiest tasks in the monastery. As a Dominican religious Margaret practiced a life of extreme asceticism and stalwart service to the poor. A cult, accompanied by miracles at her tomb in the island convent, arose soon after her relatively early death in 1270. In the following year Margaret's brother, King Stephen V, requested a canonization inquiry; this was carried out and its acts were sent to Rome.
Margaret's sanctity is documented by a Vita et Miracula intended for her canonization and by the acts of her canonization trial of 1276. In response to the papal letter commissioning her canonization inquiry, these documents also testify to the efficacy of Margaret's work in countering heresy among those with who she was in contact with. Even though seventy-four miracles were ascribed to her intercession, most of them referring to curing illnesses, and even someone coming back from the dead, her canonization was put on hold.
In the 1340s Margaret received a Vita by the Dominican Garin de Gy-l'Évêque, a future Master General. This incorporated material from the canonization trial but responded to more current models of sanctity by making Margaret a mystic and by attributing to her an instance of levitation.
Though none of these efforts led directly to Margaret's canonization, her following continued in Hungary, where in 1409 the Dominican Bl. Giovanni Dominici as cardinal legate granted an indulgence to pilgrims visiting her tomb and where Dominicans celebrated her with an Office of her own. Unsuccessful attempts to canonize her were also made in 1640 and 1770.
Margaret of Hungary was canonized by Pope Pius XII on 19 November 1943, the feast day of her aunt, Saint Elizabeth of Hungary.
St. Margaret’s feast day, a festum duplex, is the day of her passing, January 18.