After the death of his father in 1434, Przemysław found himself under the care of his older brother Wenceslaus I. In 1441 Wenceslaus I succumbing to the pressures of the Polish King and undertook to convince his younger brothers, Przemysław and Jan IV to paid homage to the Polish Kingdom, once they reached adulthood. The formal division of the Duchy was made on 19 January 1445. Przemysław received the least significant part of the Duchy, the town of Toszek. His first decision as an independent ruler was caught up in conflict with the Bishop of Kraków, Zbigniew Oleśnicki, who purchased Siewierz from the Dukes of Cieszyn. The agreement signed between both parties on 18 February 1447 in Kraków, was short-lived: on 6 October 1450 Przemysław attack with his troops the Bishop's castle in Siewierz. In 1452 Przemysław supported his younger brother Jan IV in his fight against the Polish King Casimir IV. Soon the brothers's troops were defeated and they were prompted to issue a document, in which Przemysław took all the responsibility for the war, declared the freedom for all the prisoners, and paid 2,000 fines as a compensation. However, despite the truce concluded, however, Przemysław continue his attacks and forbidden the Polish merchants to enter in his domains. The definitive settlement between the Dukes and Poland took place in Gliwice soon after; under the terms of this treaty, Przemysław consent the sale of the Duchy of Oświęcim to Poland. The now relative approximation of Przemysław with the Polish Kingdom resulted in his service in the war against the Teutonic Order, from where he returned in 1456. Despite the cooperation with the Poland, Przemysław stood at the side of his brother Jan IV in his border war against King Casimir IV. After some diplomatic negotiations, on 25 January 1458 at Bytom was made a new agreement between the brothers and Poland. In 1471 Przemysław supported the candidacy of Władysław Jagiellon as King of Bohemia, and with this gained the hate of the other candidate for the throne, the Hungarian King Matthias Corvinus. It wasn't until 25 July 1479 when the Duke of Toszek received a guarantee of his government, but in exchange he was compelled to paid homage to Bohemia. The ceremony took place on 12 August of that year in Olomouc. Przemysław died in December 1484 at his newly reconstructed castle in Toszek. He was buried in the local church of St. Peter.
After his death without male issue, the Duchy of Toszek was inherited by his brother Jan IV, but almost immediately the land was confiscated by King Matthias, who claimed more dubious rights to them.
