The Chief Justice of Nigeria or CJN is the head of the judicial arm of the government of Nigeria, and presides over the country's Supreme Court and the National Judicial Council. The current Chief Justice is Olukayode Ariwoola who was appointed on 27 June 2022. He was appointed Acting Chief Justice of the Federation upon the resignation of incumbent Chief Justice Tanko Muhammad, he was confirmed Chief Justice by the Nigerian Senate on 21 September 2022. The Supreme Court of Nigeria is the highest court in Nigeria and its decisions are final. The Chief Justice of Nigeria is nominated by the President of the Federal Republic of Nigeria upon recommendation by the National Judicial Council and is subject to confirmation by the Senate of the Federal Republic of Nigeria. The CJN holds office at the pleasure of the Nigerian constitution and can only be removed from office by death or on attainment of age 70 whichever occurs first or by impeachment by the Senate of the Federal Republic of Nigeria which requires a super majority of the members of the Nigerian Senate.

The federal government of Nigeria is composed of three distinct branches: the legislative, the executive, and the judicial, whose powers are vested and bestowed upon them by the Constitution of the Federal Republic of Nigeria, the National Assembly, the president, and lastly the federal courts, which includes the Supreme Court which is regarded as the highest court in Nigeria. One of the major functions of the constitution is that it provides for separation and balance of powers among the three branches and aims to prevent the repetition of past mistakes made by the government. Other functions of the constitution include a division of power between the federal government and the states, and protection of various individual liberties of the nation's citizens.