Mubarak was the third son of 'Ala-ud-din Khilji. After the murder of Malik Kafur, who had placed Mubarak in prison in the Hazar Sutun (the palace of a thousand pillars) and tried to blind him, the latter was made by the nobles the regent of his minor brother Shihab-ud-din 'Umar, who was placed on the throne of Delhi Sultanate by Malik Kafur after Khilji Sultan’s death.
After serving as the regent for sixty-four days, Mubarak blinded his brother in 1316, and placed himself on the throne and took the title of Qutb-ud-din Mubarak Shah.
After become the Sultan, Mubarak set himself to the task of rescinding the harsher administrative policies and economic regulations of his father. As he had himself suffered the agony of imprisonment, he set the political prisoners free. As corollary, chaos, confusion and bankruptcy began to rule the roost in the Sultanate. Added to this, he indulged in indolence and pleasure immersing himself in drinking. This resulted in the disappearance of "all fear and awe of royal authority.
Mubarak Khilji was under the influence of Khusrav Khan, a low-caste (Parwari) Hindu convert from Gujarat, whom he raised to the status of wazir, maik naib and commander in chief.
During the reign of Mubarak Shah, the rebellion in Gujarat was suppressed by his father-in law Ain-ul-Mulk, who was given the title of Zafar Khan and made governor of Gujarat. The Sultan led a military campaign against the Yadavas of Devagiri ruled by Harapala Deva who was killed. Malik Yaklaki was appointed governor of Devagiri. Mubarak Khilji Shah constructed a mosque at Devagiri. A military campaign under the leadership of Khusrav Khan was sent to Telingana, which fell in the hands of the invaders. These expeditions had been described in Amir Khusro in his Nuh Sipihr which was composed during the reign of Mubarak Khilji.
These military successes went into Mubarak’s head and he ordered the killings of several members of the royal family. The Sultan proclaimed himself “the supreme head of the religion of Islam, the Khalifah of the Lord of Heaven and Earth". He took the pontifical title of al-Wasiq-billah.
However, Mubarak was not destined to rule more. He was murdered by one of Khusrav’s Parwari associates in 1320. Thus came the end of the Khilji dynasty after a rule of thirty years.