The company hasn't disclosed the size of the stake, but it's likely Uber will use its newly-forged alliance to offer new features to passengers.
Baidu has suggested its tie-up with Uber will "enable users of Baidu Map and Mobile Baidu, [our] flagship mobile search app, to connect easily with Uber driver-partners. Uber will leverage Baidu's strengths in mobile search, mobile mapping and app distribution".
Baidu has more than 500 million monthly active users on its search engine, with 240 million monthly active users on its maps.
Travis Kalanick, Uber's chief executive, said the collaboration "marks a milestone" for the company.
We’re currently in 250 cities around the world, and the Asia-Pacific region has been a key area of growth for us. Our partnership with Baidu—a premier global brand—reflects our commitment to the region and the growing community of Uber riders and driver-partners here.
The cab app has a presence in nine Chinese cities, but has had trouble in cities such as Hong Kong, where Uber's cabs are struggling to undercut the local red-and-white taxis.