Brazil elects on the national level a head of state — the president — and a legislature. The president is elected to a four-year term by absolute majority vote through a two-round system. The National Congress (Congresso Nacional) has two chambers. The Chamber of Deputies (Câmara dos Deputados) has 513 members, elected to a four-year term by proportional representation. The Federal Senate (Senado Federal) has 81 members, elected to an eight-year term, with elections every four years for alternatively one-third and two-thirds of the seats. Brazil has a multi-party system with a high effective number of parties and political fragmentation. Often no one party has a chance of gaining a majority alone, and so they must work with each other to form coalition governments.

A presidential candidate in Brazil needs to gain fifty per cent plus one of votes to be named as winner. A second-round runoff is mandated if no candidate receives fifty per cent plus one of votes.

Deputies are elected to the Chamber of Deputies using a form of party-list proportional representation known as the open list. Seats are distributed in 27 multi-member constituencies based on the Federation Units (26 States and the Federal District), ranging from 8 to 70 seats. Seats are allocated through the D'Hondt method.

Senators are elected to the Federal Senate with a plurality of the vote in a first-past-the-post system, which is not proportional. Three senators are elected for each state and for the Federal District.

In lower levels of government, the state legislative assemblies and city councils are elected using an open list proportional representation system. Seats are allocated using a version of the D'Hondt method where only parties who receive at least V/n votes (where V is the total number of votes cast and n is the total number of seats to be filled) may win seats in the legislature.

Voting in Brazil is compulsory for all literate citizens over 18 and under 70, and optional for citizens who are aged 16 and 17, older than 70 or illiterate. Brazil introduced compulsory voting into its Electoral Code in 1932 and lowered the voting age from 18 to 16 in the 1988 constitution. The 1988 constitution also granted voluntary suffrage to the illiterate citizens of Brazil.

Electronic voting in Brazil was first deployed in 1996, in pilot use in dozens of municipalities including in the state of Santa Catarina, and was progressively expanded nationwide. The system is administered by the Electoral Justice (Justiça Eleitoral), headed by the Superior Electoral Court (Tribunal Superior Eleitoral, TSE) and the Regional Electoral Courts (Tribunais Regionais Eleitorais, TREs), which are responsible for voter registration, biometric identification, vote collection, result tabulation, transmission and consolidation of results, and formal certification of the outcome. The electronic voting machine used at polling places (Portuguese: urna eletrônica) is just one component of this broader infrastructure. Its design emphasizes operational simplicity for voters — often compared to the usability of a public phone booth, and it functions as a dedicated terminal that records each ballot locally, encrypts and stores the vote, and produces a digital tally at the end of the day. As of 2023^[update], Brazil is the only country in the world to conduct its elections entirely through electronic voting.

Brazilian legislative elections (Chamber of Deputies), 1982–2018