In its annual UK forecasts, the media-buying agency has predicted that the additional revenue - in cash and barter deals - will be booked into the market next year.
Group M forecasts that the Olympics will then bring in an extra £200m in 2008. The London Games hope to raise £750m in the run-up to 2012.
The additional revenue will help to significantly boost the sponsorship market, which is already in good health. Group M has predicted that TV sponsorship will have increased by £3m this year and £5m in 2007.