The agency's primary function will be to run the Nissan business in China.
Based in Guangzhou, with a workforce of around 60, it will be a separate agency from its parent companies.
Nissan has predicted that by 2008, China will be its third-largest market behind Japan and the US.
Keith Smith, the regional chairman for TBWA\Asia-Pacific, said: "It is a great opportunity for us to continue to build close links with Hakuhodo. Our complimentary skills should hopefully ensure that Nissan goes from strength to strength in China."