Host India will seek to balance its ties with China and Russia against its growing partnerships with the US and other Western powers.
Russian President Vladimir Putin, Chinese President Xi Jinping and Iranian President Masoud Pezeshkian are among the leaders confirmed to attend.
BRICS is a grouping of major emerging markets and developing countries, named after an acronym for Brazil, Russia, India, China and South Africa.
It has expanded from its original membership to include 11 countries that together represent about half the world's population and a large share of its energy, resources and economic output.
Experts say its growing size has also exposed divisions as its members want greater influence in the global order but often have competing political, economic and foreign-policy interests.
BRICS faces divisions over Iran and Ukraine
The conflicts in Iran and Ukraine are likely to highlight those divisions. Iran is a member of the expanded BRICS, while Russia remains one of its most influential members. China has close ties with both countries, while India maintains relations with Russia, Iran, the United States and Europe.
That diversity makes it difficult for BRICS to take a strong common position on major conflicts. The grouping includes countries with competing regional ambitions, including India and China, Iran and Saudi Arabia, and Egypt and Ethiopia, as well as other nations from the global south.
"The global south is not a homogeneous entity," said Praveen Donthi, senior analyst with the International Crisis Group. "Hence, the grouping will find it hard to manage and mediate in these conflicts."
Russia's war in Ukraine has already exposed the limits of India's ability to balance competing interests. New Delhi has maintained close ties with Moscow, including through energy and defence pacts, while also deepening its strategic relationship with Washington.
The South Asian nation has consistently called for dialogue and diplomacy rather than taking sides.
The Iran-U.S. conflict poses a similar challenge. BRICS members have differing ties with Washington and interests in the Middle East, making a unified response difficult.
China and Russia have backed Iran in international forums, while India has taken a cautious approach. Saudi Arabia and the UAE have their own tensions with Tehran.
For India, the summit is an opportunity to manage its relationship with China. Ties have improved since border tensions escalated in 2020, but China remains India's largest strategic rival.
President Xi's visit to New Delhi, his first in seven years, could help consolidate the recent diplomatic thaw but there are few signs of a recovery in trade and business ties.
"The upcoming summit offers India an opportunity to engage with China, make progress on outstanding bilateral issues," Donthi said.
India also has an interest in preventing BRICS from becoming an explicitly anti-Western bloc.
New Delhi has strengthened ties with the US, Israel, Japan, Australia and Europe while maintaining its longstanding relationship with Russia.
BRICS' growing membership also gives it considerable weight, but its influence will ultimately depend on whether the members can agree on practical steps.
The group has called for changes to global financial institutions, greater representation for developing countries and alternatives to Western-dominated systems. Yet its members often disagree on how to achieve those goals.
Donthi said BRICS' success could be measured in smaller steps. These include keeping the expanded group together, improving ties with China, and deepening trade and financial cooperation.
The grouping could also show that it can give developing countries a platform without forcing them to choose between Western and non-Western blocs, he said.
