The study reveals and analyses the most significant historical sources about the religious activity and the death of Constantin Brâncoveanu, the ruler of Wallachia. Our investigation is focused on the execution of the Romanian sovereign, ordered by the Sultan Ahmed III, in 1714, and it is based on the informations from the witnesses’ testimonies on the tragic event. Also, we intend to outline the main directions of his religious activity.          First, we noticed the abundance of sources, as the bloody and cruel execution shocked and horrified the witnesses and also the press of the time. The informal notes of the Dutch, French or German ambassadors to Istanbul, reporting the events, also insist on the period of the imprisonment, during which Brâncoveanu and his family were tortured in order to disclose their fortune. The historical sources reveal the possibility offered to Constantin Brâncoveanu to save his life by converting to Islam, an opportunity which was repeatedly turned down by the Romanian ruler. As if all this was not enough, the sons were killed, one by one, in front of their father, who was encouraging them not to abandon their Orthodox faith. Under the given circumstances, his death was a real martyrdom, for Brâncoveanu preferred death to apostasy. He was praised as a martyr soon after his death and a beautiful akathist hymn was written in his honour by the metropolitan of Heracleea and the future Ecumenical Patriarch, Calinic.          The martyrdom of the Romanian ruler crowned a life dedicated to Orthodoxy. His constant activity of supporting the Orthodoxy was achieved by several specific methods. He had built churches and monasteries all over the Orthodox world, in the Romanian Principalities and also in Oriental countries, which were under Muslim government. Constantin Brâncoveanu endowed the churches with estates, money, religious books and objects and liturgical vestments as well. He established in Wallachia, Transylvania and also in Oriental places, as Alep for example, printing houses where important liturgical and apologetical books were printed.