"The Brazilian government announces Vietnam's official accession as a partner country," the ministry said in a statement.
Brazil presides over the group this year, TASS reported.
According to the ministry, Vietnam has become the association's 10th partner. The country "shares with BRICS members a commitment to a more inclusive and representative international order," the ministry said.
"With a population of nearly 100 million people and a rapidly developing economy that is firmly integrated into global value chains , Vietnam is an important player in Asia," the statement said.
The key event of the Brazilian BRICS presidency will be the BRICS summit in Rio de Janeiro scheduled for July 6-7.