The central administration of the Delhi Sultanate included the office of the Sultan, who was the head of the state, the ministers and other officers like the naib, the vazir, Diwani-i-risalat, Dabir-i-khas, Ariz-i-mumalik, Sadr-us-Sudur, Qazi-ul-quzat and Barid-i-mumalika. Besides, there were also several other departments and the Sultan appointed their officers to carry on specific duties.
Sultan was the head of the state and enjoyed unlimited powers in every field of state activity. There was no law of succession during the period of the Delhi Sultanate. It was not obligatory that the eldest son or the daughter of the Sultan should succeed the father. However, convention developed from the reign of Sultan Iltutmish that the throne belonged to the eldest son or the daughter of the Sultan. The Sultan also had the power to nominate any one as his successor to the throne. Thus the principle of hereditary succession and nomination of successor by the Sultan came into vogue. Rulers like Razia Sultana, Shihab-ud-din Khilji, and Tughlaq Shah were accepted on the basis of one or other of these principles. But the experiment of placing a female or a minor on the throne however did not work. Therefore, the practice developed that the right of heredity was to be accepted only in cases of competent successor. In case a competent successor was not available the nobles were given the right to choose the Sultan. Besides, the sword also decided the issue of succession. Ala-ud-din Khilji, Khizr Khan and Bahlul Lodi got the throne by force.
The Sultan, according to the power bestowed upon him behaved like a autocrat. The Sultan was the supreme master of the state and all legislative, executive and judicial powers were concentrated in his person. He was also the highest commander of the army. All ministers, nobles and other officers of the state were appointed, promoted and dismissed by him. His order was the law of the state. But, these were his legal powers. Their effectiveness in practice depended on his military strength. The nobility also wielded authority particularly if the Sultan was weak. The Ulema, being the interpreter of Islamic laws, also influenced the policy of the Sultan. Only Ala-ud-din Khilji and Mubarak Khilji refused to accept the interference of the Ulema in matters of the state. Apart from preservation of peace and order within the empire and its protection from foreign invasions, the important duty of the Sultan was safeguard and propagation of Islam.
There were different ministers and other officials who assisted the Sultan in administering the state. The post of the naib was created during the reign of Sultan Bahram Shah. The nobles had chosen one among themselves as naib who, in fact, enjoyed all powers of the state. However, this post had purpose and meaning only during the reigns of weak rulers. In such cases the post of the naib was next only to the Sultan and was above the vazir. The influential Sultan either abolished the post or gave it to a noble just to honour him as it was done by Ala-ud-din Khilji. In cases like this the naib had no special powers in administration.
The vazir was the Prime Minister of the state. He basically headed the finance department called the Diwani-i-vizarat and had the power not only to supervise the income and expenditure of the state but all other departments as well. Whenever there was no post of naib, the position of the vazir was next to the Sultan. He supervised the complete administration and looked after whenever the Sultan fell ill or was out of the capital, appointed officers to special posts and performed various other duties. Many officers and subordinates assisted him and the chief among them were naib-vazir, mushrif-i-mamalik, and mustaufi-i-mamalik. Ariz-i-mumalik was the head of the department of diwani-i-arz and in that capacity was the controller-general of the military department. He recruited soldiers, fixed their salaries, arranged for their supplies and inspection and maintained the descriptive rolls of horses and men.
Dabir-i-khas headed the department of diwan-i-insha. All formal or confidential correspondence between the Sultan and the rulers of other states or subordinate chiefs, governors and officials was carried on by his department. A number of Dabirs (writers) helped him in his work. The minister of foreign affairs was Diwan-i-risalat, who looked after the political relations with foreign states and wellbeing of foreign diplomats and ambassadors. Sadr-us-Sudur was the head of the religious department. His primary duties were the propagation of Islam, observance of its principles and protection of the privileges of Muslims. He controlled the finances of the tax called zakat which was a religious tax on the Muslims. He provided financial help to mosques, maqtabs and Muslim scholars and saints. He also looked after the distribution of charity by the state.
Qazi-ul-quzat was the highest judicial officer in the state after the Sultan. He had both original and appellate jurisdiction. Generally, the offices of Sadr-us-sudur and Qazi-ul-quzat were combined in one person. Barid-i-mumalika was the head of the intelligence and postal department. He was responsible for the espionage system, collection of news and their quick dispatch and disposal.
There were also other departments where officers were appointed by the Sultan to carry out specific duties. For example, Muhammad Bin Tughlaq created the department of diwan-i-amir kohi or the department of agriculture. The Vakil-i-dar-mahal looked after the officials of the palace; the Barbak maintained the tradition of the court and its glamour; Amir- i-hajib looked after the visitors to the Sultan; Amir-i-shikar-i-shahi arranged for the hunting parties of the Sultan; Amir-i-majlis-shahi looked after the festivals of the state; and Sar-i-jahandar was the Sultan`s bodyguards. The Sultan also maintained different karkhanahs to manufacture different articles such as cloth, arms etc. and various officers were appointed. They did not enjoy the rank of ministers but as a few of them looked after the personal security and comfort of the Sultan, they were very close to him and wielded good influence.