The amount of money spent on ads in social games could top $220 million (£140m) this year, according to digital analyst eMarketer.
Although most social games rely heavily on micro and in-game transactions of virtual goods, eMarketer said estimates of ad spend are conservative as companies like Zynga and Playdom increasingly allow brands access to their millions of users.
eMarketer estimated that the US would account for $142 million of 2010's $220 million, with the remaining $78 million spent outside of the region.
The US figures are down slightly on last year, when North America accounted for $144 million. But spend outside of the US has almost doubled from $39 million in 2009, when worldwide spend totalled $183 million.
Next year, worldwide ad spending in socials gaming is expected to top $293 million, with the US accounting for $192 million and the rest of the world $101 million.
Recent research by Nielsen showed that users in the US spent 407 million hours playing games online last month, with time spent on social networks and blogs bringing that figure to 906 million hours.