Nasiruddin Mahmud was the posthumous child of the eldest son of Iltutmish named Shahzada Nasiruddin. Due to the intense love for eldest son, Iltutmish gave same name to his eldest son to his grandson. Iltutmish wanted the young baby to be considered his son and not grandson for dynastic reasons. So we should not be surprised at the fact he was called the son of Iltutmish all his life. Nasiruddin was a young lad of seventeen at the time of accession to the throne. He had no ambition to become a king but was rushed to the capital disguised as a woman along with his mother and was placed on the throne by the conspirators, who had killed Masud Shah. Balban was one of the patrons of Nasiruddin.
Nasiruddin was an educated and intelligent man of gentle and pious nature. He was devoted to his faith and lived a virtuous life. He had never more than four living wives and no concubines. He kept himself busy with religious activities. He was also a good calligraphist, as a past time, he used to write copies of the Quran which gave currency to the popular belief that he made his living by selling his scripts alone. He adopted an attitude of complete self surrender towards the man in power and played a role of puppet in their hands. Rather it would be more appropriate to say that Nasiruddin was the constitutional Chief Executive of the Turkish oligarchy. That is why he became more acceptable to all the nobles who were left free to settle the matters of state between themselves. As for as the independent status of Nasiruiddin is concerned, Isami tells us that sultan expressed no opinion without their (Shamsi nobles) permission. He did not move his hands or feet except at their orders. He stares clearly that Ulugh Khan (Balban) served the king and controlled all his affairs. The king lived in the palace and Ulugh Khan governed the empire.