Islamic republic is the name given to several states in the Muslim world including the Islamic Republics of Pakistan, Iran, Afghanistan, and Mauritania. Pakistan adopted the title under the constitution of 1956. Mauritania adopted it on 28 November 1958. Iran adopted it after the 1979 Islamic Revolution that overthrew the Pahlavi government. Afghanistan adopted it after the 2001 overthrow of the Taliban. Despite the similar name the countries differ greatly in their governments and laws.

The term "Islamic republic" has come to mean several different things, some contradictory to others. Theoretically, to many religious leaders, it is a state under a particular theocratic form of government advocated by some Muslim religious leaders in the Middle East and Africa. It is seen as a compromise between a purely Islamic Caliphate, and secular nationalism and republicanism. In their conception of the Islamic republic, the penal code of the state is required to be compatible with some laws of Sharia, and not a monarchy as many Middle Eastern states are presently. In other cases, it is merely a symbol of cultural identity, as was the case when Pakistan adopted the title under the constitution of 1956. In fact many argue that an Islamic Republic strikes a middle path between a completely secular and a theocratic (and/or Orthodox Islamic) system of government.

Iran's Islamic republic is in contrast to the semi-secular state of the Republic of Pakistan (proclaimed as an Islamic Republic in 1956) where Islamic laws are technically considered to override laws of the state, though in reality their relative hierarchy is ambiguous.

Pakistan was the first country to adopt Islamic prefix to define its republican status under the otherwise secular constitution of 1956. Interestingly enough, despite this definition, the country did not have state religion until 1973, when a new constitution, more democratic but less secular, was adopted. Pakistan only uses the "Islamic" name on its passports and visas. All government documents are prepared under the name of the Government of Pakistan, however, Islamic republic is specifically mentioned in the Constitution of 1973. As per the Constitution of Pakistan, part IX, article 227 " All existing laws shall be brought in conformity with the Injunctions of Islam as laid down in the Quran and Sunnah, in this Part referred to as the Injunctions of Islam, and no law shall be enacted which is repugnant to such Injunctions ".