Details of the acquisition were not disclosed, Xinhua reported.
Launched in 1997, Quickoffice provides mobile office document software for devices running Apple's iOS and Google's Android operating systems, allowing users to open, view and edit Microsoft Office files with complete document data integrity.
The company said its product has been downloaded on 300 million devices so far in 180 countries.
Analysts said Google may release its own mobile office software suite as Microsoft appears to hold back Office from other mobile platforms, rather than its Windows 8.
Quickoffice is Google's second major acquisition this week. On Monday, the search giant announced that it had purchased the instant messaging firm Meebo.
According to an earlier report by technology news site AllThingsD, the price Google paid for Meebo is about $100 million.