The Constitution of the Federative Republic of Brazil (Portuguese: Constituição da República Federativa do Brasil) is the supreme law of Brazil. It is the foundation and source of the legal authority underlying the existence of Brazil and the federal government of Brazil. It replaced the autocratic 1967 constitution capping 21 years of military dictatorship and establishing Brazil's current republic, often referred to as the New Republic. Made in the light of the Brazilian transition to democracy, it resignified the role of the state in the citizens' lives, providing a vast system of human and individual rights protection, social welfare, and democratic tools.

The 1988 Brazilian Constitution is the seventh enacted since the country's independence in 1822, and the sixth since the proclamation of the republic in 1889. It was promulgated on 5 October 1988, after a two-year process in which it was written from scratch.^{[citation needed]}

The current Constitution of Brazil was drafted as a reaction to the period of military dictatorship, and sought to guarantee individual rights and restrict the state's ability to limit freedom, to punish offences and to regulate individual life. Among the new constitutional guarantees are the errand of injunction and the habeas data. It also anticipated the existence of a Consumers' Defence Code (enacted in 1990), of a Children's and Youth Code (1990) and of a new Civil Code (2002).

It was the first constitution to demand severe punishment for breaches of civil liberties and rights. Consequently, Brazil later approved a law making the propagation of prejudice against any minority or ethnic group an unbailable crime. This law provided legal remedy against those who spread hate speech or those who do not treat all citizens equally. This second aspect helped disabled people to have a reserved percentage of jobs in public service and large companies, and Afro-Brazilians to seek reparation for racism in court.

Breaking with the authoritarian logic of the previous Constitution, it made unbailable crimes those of torture and of actions directed against the democratic state and the constitutional order, thus creating constitutional devices to block coups d'état of any kind.

The Constitution also established many forms of direct popular participation besides regular voting, such as plebiscite, referendum and the citizens' initiative. Examples of these democratic mechanisms were the 1993 plebiscite concerning the form of government, where the presidential system was confirmed, and the 2005 firearms and ammunition referendum.

The mention of God in the preamble of the Constitution (and later on the Brazilian currency) was opposed by most leftists as incompatible with freedom of religion because it does not recognize the rights of polytheists such as some indigenous peoples or of atheists. The Supreme Federal Court has ruled that this commission of the protection of God was not unconstitutional since the preamble of the constitution is simply an indication of principles that serves as an introduction to the constitutional text and reflects the ideological conceptions of the legislator, falling within the scope of political ideology and not of the Law.

The Federal Constitution of 1988 is criticized in the doctrine for being very extensive, long-winded, and analytical. This characteristic forced the Constitution to be amended several times, in politically costly processes, to adapt to changes in society.