It now offers tools to allow US firms to sell on the business-to-business platform in the US and globally.
The move will allow Alibaba, traditionally China-focused, to compete with global e-commerce giants like Amazon.
Alibaba.com says it has 10 million active business buyers in more than 190 countries and regions.
As part of the announcement on Tuesday, Alibaba.com said US produce firm Robinson Fresh would be joining the platform on 23 July.
It follows a "strategic collaboration" between Alibaba.com and US offices supply firm Office Depot.
Previously, US businesses mainly bought from Chinese sellers on the Alibaba.com platform, which caters to small and medium-sized firms.
The new tools, which include an online payments system, will give American firms access to new customers in China and around the world.
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