Baidu Inc's large investment in mobile gaming and app distribution has started to pay off, with the search giant earning 20 percent of its revenue from mobile business in the fourth quarter of fiscal year 2013.

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Baidu, which announced its unaudited financial results for the fourth quarter late on Wednesday, said 20 percent of revenue in Q4 came via mobile, up from 10 percent in Q2.

"2013 was marked by our entry into new areas and significant progress in mobile, as we invested aggressively to build Baidu's position in search, app distribution and location-based services," said Robin Li, chairman and chief executive officer of Baidu.

"Our efforts to drive mobile adoption among customers gained significant traction throughout the year. In the fourth quarter, mobile accounted for over 20 percent of total revenue."

Baidu reported total revenue of 9.52 billion yuan ($1.57 billion) for the fourth quarter of 2013, a 50.3 percent increase from the corresponding period in 2012.

The strong growth of Q4 helped Baidu close fiscal year 2013, which ended on Dec 31, 2013, with total revenue of 31.94 billion yuan, up 43.2 percent on fiscal year 2012.

Net income attributable to Baidu in 2013 was 10.519 billion yuan, representing a 0.6 percent increase from 2012.

Baidu currently expects to generate total revenue ranging from 9.24 billion yuan to 9.52 billion yuan for the first quarter of 2014, representing a 54.8 percent to 59.5 percent year-over-year increase, according to the company's press release.