The UK-based set led by chief executive Sir Martin Sorrell (pictured) was helped by its acquisition of top stage marketplace explore company TNS in October 2008.
The addition led to a 13% increase in intensity in WPP's calendar time revenue – from $10.7bn in 2008 to $12.1bn in 2009.
View rotund list of economic results
US-based Omnicom suffered a 12% decline in revenue from $13.4bn in 2008 to $11.7bn in 2009 as, along with the have a break of the industry, it was destroy by on sale client consume.
However, Omnicom was the nearly everyone profitable company in the rankings, which were compiled by Marketing Services Financial Intelligence.
Despite Omnicom's post-tax profit falling 21% and WPP's holding steady, the earlier weighed in with a build of $793m to the latter's $666m.
Publicis Groupe claimed third place from US-based Interpublic in revenue provisions, with immediately a 4% decline to $6.4bn compared to Interpublic's 13% decline to $6bn.
Japan's Dentsu, France's Havas and the UK's Aegis occupied the subsequently three spaces.
Dentsu was strong on profitability, with post-tax profits of $341m outstripping the combined profits of Havas, Interpublic and Aegis.
It placed fourth in the level of post-tax profits similar to Publicis Groupe, which earned $573m.