Russian President Vladimir Putin will oversee the signing of a $5 billion-deal to supply Delhi with S-400 air defence systems.
"The president is leaving for India on October 4," Putin's top foreign policy aide Yury Ushakov told reporters.
"The key feature of this visit will be the signing of the agreement to deliver S-400 air defence systems," he said. "The value of the contract will be more than USD 5 billion."
Moscow has been negotiating to sell the S-400 long-range surface-to-air missiles to India for months.
The sale has irked India's defence partner Washington, which has wanted to wean the Centre off Russian technology, and a senior Pentagon official said in August that sanctions against India would come under consideration if its purchase goes through.