[9] ED's ideology was based on a broad left-wing concept: it advocated that socialism had to be built gradually and legally, through the defence of democracy and a national identity.

PSB opposed the centralism and authoritarianism of Vargas, as well as the rigid labour union structure supported by PTB.

[9] It advocated immediate reforms, such as the nationalisation of economically strategic areas, the expansion of workers' rights, the ensuring of public health and education, and the development of democracy through means of popular participation.

[9] Through them, Socialist militants could get involved in the party project, discuss national issues and form the orientation and the target of partisan action.

The PSB had limited legislative representation between 1947 and 1964, but in 1962 it elected one Senator, Aurélio Viana defeated the UDN's candidate, Juracy Magalhães in Guanabara State.

Most Socialists joined the Brazilian Democratic Movement (MDB), the only opposition party recognised by the military regime.

In 1990, Pernambuco Governor Miguel Arraes joined the party, giving the PSB a certain electoral boost in subsequent elections.

In 2000, the Governor of Rio de Janeiro, Anthony Garotinho joined the PSB following a feud with Leonel Brizola, the leader of the Democratic Labour Party.

After that election, the PSB had three Governors: Cid Gomes (Ceará), Eduardo Campos (Pernambuco) and Wilma de Faria (Rio Grande do Norte).

These positions led many traditional socialists and social-democrats in Brazil to leave the party for more left-wing outfits such as the PSOL and PDT.

The party later voted in favour of the impeachment of Dilma Rousseff and formed a coalition government with Brazil's new president, Michel Temer.

On 30 August 2019, the Brazilian Socialist Party withdrew from the Foro de Sao Paulo, denouncing its support of Nicolas Maduro's presidency.

[14] In 2022, Geraldo Alckmin joined the Brazilian Socialist Party and ran as Lula's running mate in the 2022 general election, winning the run-off.