The son of Kazimierz I and Eufemia, the daughter of Trojden of Mazovia. Most probably by personal choice rather than as a result of external pressure he chose a clerical career. This conclusion derives from the fact that as Przemysław's elder brother he was first in line to inherit the Duchy of Cieszyn. Bolesław gained the support of the King of Bohemia, John of Luxembourg, who managed to gain papal assent for the acquisition of a canonry and a prebendary in the cathedral of Cracow or Wrocław for Bolesław. Bolesław, as a Wrocław cleric, first (in 1349) was given a canonry in Cracow, and then, sometime after 11 June 1355, supported by Charles IV, a canonry in Wrocław. In 1353 he became a chaplain of King Charles IV and along with this received the provostry of the Church of All Saints at the castle in Prague. A promising clerical career was cut short by his early death.

(MBVat, vol. 1, no 534, MPVat, vol. 1, p. 426, vol. 3, no 326, 353, K. Jasiński, Rodowód, p. 139)