The deal, which will push out a 14-year joint venture between Beijing Guoan and WPP's Grey Global Group, will cement a merger of DDB China with Beijing Guoan Advertising Corporation.
The new partnership, DDB Guoan Communications, will be headed up by Yan Gang, Citic Guoan executive vice-chairman, who is also director of the China Advertising Association.
The agency will be based in Beijing, with offices in Shanghai and Guangzhou, while Omnicom will own a majority of its shares.
Citic Guoan oversees more than 75 companies in China and is understood to control over $2.2bn in assets.
The partnership will be welcomed by Omnicom, which has been trying to move into the Chinese market to challenge the might of WPP, which has made a slew of acquisitions in the region.
It will help Omnicom, which is headed by president and CEO John Wren, raise its profile in China, where none of its creative agencies has a large presence, and give the firm a greater local expertise.
Citic has played a role in China's open-door policy and become one of the most influential business conglomerates in China.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .