Havas Worldwide Beijing confirmed that Chen will be leaving around the fourth week of January and that it's looking for a replacement.
At DDB Guoan Beijing, Chen's title will be vice-president and group MD. He will report to Richard Tan, North China CEO. The MD role has been vacant for three years since Tan moved up to his current position.
Chen joined the agency, which was then called Euro RSCG Beijing, in 1998 and rose through the ranks from account director to MD. He left in 2005 to join a local agency, Shunya Advertising, as its VP and MD, before rejoining Euro RSCG in February 2010. (Euro RSCG rebranded as Havas Worldwide in 2012.)
Update, Jan. 7: Added Chen's full title.