He was the third son of the Polish high duke Henry II the Pious, by his wife Princess Anna, daughter of the Přemyslid king Ottokar I of Bohemia.

After the heroic death of his father at the Battle of Legnica on 9 April 1241, Henry III was still a minor and found himself under the care of the mother together with his youngest brothers Konrad and Władysław.

Bolesław, as the older brother, had the opportunity to choose his district; he decided on Legnica, because gold had been discovered in the Kaczawa and Wierzbiak Rivers.

Bolesław II may have hoped that Henry III encountered serious difficulties with Wrocław (which he received in the division), so at the end the Duchy would come back to him.

An additional point of the agreement was the obligation to offer hospitality to the younger brothers, Konrad and Władysław, who were destined to the espiritual career.

Henry III's successful attempts to make Władysław entered in the Church had a total contrast with the relations between Bolesław and Konrad.

Defeated, Bolesław II was forced to give the district of Głogów to Konrad, who wished to enforce Henry III's intervention over Legnica in 1250.

All these treatments are not expected to take effect over the Duke of Wrocław, however, as Henry III in his relations with the brothers now sought to avoid open conflicts.

Another manifestation of Henry III's rule was the intensive German colonization of Lower Silesia, which significantly contributed to the growth and prosperity of his Duchy.

The pretext emerged in the mid-year 1266 when they tried to forced a division of the Duchy of Wrocław between Henry III and his brother Archbishop Władysław of Salzburg.

The Polish historian Jerzy Mularczyk, had two possibles leaders of the revolt: first, the Bishop Thomas of Wrocław, who, taking advantage from Henry III's apparent weakness, tried to strengthen the position of the church; but after watching how the Duke concentrated all the power in his hands and stripped the nobility from his privileges, he feared that this also happened with the Church hierarchy, which certainly he did not permit.

Henry III's dying request to extend the rule of Władysław's regency was made with the clear purpose to reduce the suspicion of guilt against him.

In addition to the Kronika polska, the mysterious death of Henry III was written even on his tombstone: Anno domini Millesimo, Nonas Decembris obiit veneno inclitus dux Wratislaviensis Henricus tertius, secundus filius secundi Henrici, a Thartaris.