Under the terms of the deal, which is pending approval from the Central Bank of Russia, KBC will pay $1.03 billion for the stake and will retain the company's current management.
Meanwhile, the remaining 7.5 per cent stake in Absolut will be retained by the World Bank Group.
Commenting on the deal, Andre Bergen, KBC chief executive, said: "KBC's long-term strategic plans entail further expansion in the markets of emerging Europe. Russia is therefore an extension of our existing presence."
News of the impending acquisition comes as KBC also announced that its broking division KBC Securities is to acquire Serbian brokers Hipobroker and Senzal and corporate finance company Bastion with the intention of merging the three companies into KBC Securites Serbia.
Since being formed in 1993, Absolut has established itself as the seventh-largest non-state owned bank in Russia.