Bolesław was the son of Mieszko I and Dobrawa. He was born in the year 966 or 967. He was married several times, one of his wives was Emnilda, the daughter of Dobromir a western-Slavic king.

Even during his Father's reign, Bolesław took part in many wars, and it is possible that he administered the territory of Krak�w by leave of his father. After the death of Mieszko, Bolesław united all the Polish territories under his reign and he ruled a unified Poland for thirty three years. During his rule, he earned the name of Chrobry and the name of Great. During the beginning of his reign he granted help to the bishop Wojciech of the Slavs which, had to leave the Czechs where his family was defeated over the control of the territory of Przemysł. Bolesław looked after the welfare of Wojciech and helped him to prepare details of a mission to Pomerania and to Prussia. Wojciech died a very horrible death at the hands of the pagans he was preaching to and underwent much suffering and was made a saint in the year 999. Bolesław stood much to gain politically. He reached an agreement with the papacy to establish the Archbisphoric at Gniezno and three others in the cities of Krak�w, Wrocław, and Kołobrzeg to add to the one already in Poznań. With his persistend diplomatic means he persuaded Otto III to allow a pilgrimage to the tomb of Saint Wojciech. However the establishment of the Archbisphoric of Gniezno also established Polish sovereignty and Bolesław was symbolically crowned there. The only thing that Bolesław was lacking was the coronation by an actual Pope, so Pope Sylvester II sent Bolesław a royal insignia and was crowned officially in the year 1024, just a year before his death.

To try to unify the western Slavs, Bolesław had to fight numerous wars. Over time he took over the Czechs (1003). This led to guerilla warfare and open-field battles with the Germans. These wars lasted many decades. They finally ended in the year 1018. The German Emperor Henryk II, recognized the sovereignty of Poland and granted the lands near the Oder river to the Poles. Bolesław also extended Poland's boundaries eastward by his battles for the city of Kiev in the Ukraine in the year 1018. The boundaries of Poland streched from Szczeciń in the west, Moravia in the south, and toward Russia in the east.

Bolesław did not divide his kingdom for his children, instead he bestowed the entire kingdom in whole to his son Mieszko II. Bolesław Chrobry died in the year 1025 and is buried under the Cathedral in Poznań.