MediaCom, Carat, Dentsu and Visioncn have all been shortlisted for the account, with the successful agency being responsible for helping the brand gain a headstart on rivals China Mobile and China Telecom in the 3G network sector.
China Unicom recently launched its 3G offering, called Wo, through a large-scale TV campaign and a 1,000-phone giveaway.
The company has also agreed a partnership deal with Apple to introduce the iPhone to the 3G market.
In the 2G market, China Unicom is the smallest of the big three operators, with a market share of around 10 per cent.