The highest officer under the Turkish / Khilji Rulers of the Delhi Sultanate was

Answer :- Naib-i-Mulk

The post of Naib-i-Mamlakat, equivalent of the English term ‘regent’ was created by the Turkish slave rulers. It was later called called Naib- i-Mulk or Malik Naib (under Khilji). The Sultan dominated the central government as he was the legal head of the state and acted as the chief executive and the highest court of appeal. The Sultan was assisted by number of ministers. In them Naib-i-Mulk or malik naib held highest stature in the central government of the Sultanate.