The company said net profit rose to $42.3 million, or $1.22 a share.
Excluding items, the company earned $1.31 a share; analysts, on average, were expecting the company to post a penny more in profit.
Revenue jumped 58% to $132.7 million, in line with expectations the company set Dec. 11 when it took down top-line projections at the time of $151 million to $155 million.
Baidu said the number of active online marketing customers during the fourth quarter was more than 197,000, an increase of 1.5% from the previous quarter.
Revenue per online marketing customer for the fourth quarter was about $674, which was down 2.1% from the third quarter but up 24.3% from a year earlier.
Baidu said the sequential decrease in revenue per customer was primarily due to a portion of customers in the medical and pharmaceutical sector being temporarily removed from paid search results during the quarter.
In November, Chinese television reports had asserted that some unlicensed medical companies appeared high in Baidu's search results due to their willingness to pay for popular keywords, ultimately forcing their removal from search listings until licenses could be validated.
A large portion of these customers have resumed using the company's services since then, Baidu said.
The company didn't give an immediate estimate for first-quarter results, but a projection was expected during the company's conference call with analysts.
"Going into 2009, we will continue to focus on growing the top line and taking a disciplined approach to costs while making investments for long term gains, particularly in the areas of user experience, monetization, sales efficiency and branding," said Baidu Chief Financial Officer Jennifer Li, in a press release.
Shares of Baidu, which climbed 4.7% in the regular session, were off 0.8% in recent after-hours trading to $127.10.