The announcement about the Indonesian membership was made on Monday by Brazil, which is currently the chairman of the group.
Indonesia "shares with the other members the desire to reform global governance and contribute to cooperation" between countries in the Southern Hemisphere, said the Brazilian Foreign Ministry in a statement.
The informal decision to welcome Indonesia was made already at the Brics summit in South Africa in 2023, but has only now been formalized. Previously, Iran, Egypt, Ethiopia, and the United Arab Emirates have become full members.
The Brics group, which was formed in 2009, led a dwindling existence for several years, but the group has regained influence. One reason is the increased number of member countries.
At the group's latest summit in Kazan, Russia, last year, the Brics countries emphasized the need for an international trade currency as an alternative to the US dollar.
The Brics countries also want to see a changed global balance of power.
Indonesia, with over 280 million inhabitants, is the world's fourth most populous country.
