The investment in Kakao Pay comes less than a month after Ant bought US-based payments operator MoneyGram for around USD 880 million and struck a partnership deal with Thailand's Ascend Money in November.
Ant is behind Alipay, which accounts for 80 per cent of electronic payments in China where it is used for e-commerce at Alibaba online venues and a large number of mobile applications.
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"South Korea is an important market for Ant Financial in its global expansion," said Douglas Feagin, president of Ant Financial International, in a joint statement with Kakao.
The companies said the investment was part of a larger strategic partnership to connect Ant's 450 million users worldwide with Kakao Pay, which currently has more than 14 million subscribers.
Kakao, best known for its mobile messaging service Kakao Talk, has more than 48 million users globally.
It decided in January to spin off its mobile payment service Kakao Pay into a separate entity which offers services such as bill payment and remittance.
Shares in Kakao soared 4.25 per cent to 88400 won in afternoon Seoul trading today.