South Korean e-commerce giant Coupang said Wednesday that it has won a $1 billion investment from Japanese telecommunications giant SoftBank Corp., a deal that is anticipated to solidify its footing in the local online retail market and fuel global expansion plans.

Under the agreement, a SoftBank unit will make the investment in Coupang, with the deal closing in early July, the two companies said in a joint press release.

"We welcome SoftBank as a long-term partner and look forward to leveraging their global expertise and vast network to further accelerate our growth," said Coupang founder and CEO Bom Kim.

SoftBank Chairman Masayoshi Son said he "looks forward to supporting Coupang as they further revolutionize e-commerce."

With the latest investment, Coupang has secured $1.4 billion in funding over the past year.

In 2014, the company raised $300 million in an investment led by U.S. asset manager BlackRock. It also won $100 million in funding from U.S. investment firm Sequoia Capital.

Six years into its launch, Coupang has grown into one of South Korea's biggest online retailers. Its mobile payment transactions hit 1.4 trillion won (US$1.3 billion) last year, more than doubling from 600 billion won in 2013.

Coupang, a leading South Korean e-commerce operator, said it plans to use the funding to "fuel innovations in its end-to-end fulfillment service, same-day delivery network and leading mobile applications," as well as expand R&D offices in Silicon Valley, Seattle and Shanghai. (Yonhap)