The Williams Formula One team is the biggest casualty, losing £10m promised by the bank after it decided to cease all F1 sponsorship, including trackside advertising by 2010.
Other sports expected to lose out include cricket and golf, while there are understood to be negotiations in the works with individual sports stars such as Andy Murray and Jack Nicklaus about reducing the value of their contracts.
Rugby Union's Six Nations Championship will most likely be safe. RBS recently renewed its £20m contract to sponsor the title for the next four years.
Today's move had been anticipated for several weeks, after the struggling bank came under fire for its spending on sponsorship deals, despite having been bailed out with billions of pounds worth of taxpayers money.
Andrew McLaughlin, RBS group director, said: "We recognise that we are now operating in a very different economic environment and have been reviewing our activities since October. It is imperative that we respond to the reality of the situation we face."
This latest evaporation of money will come as a heavy blow to Formula One, which relies on sponsorship deals for more than 70% of its income. It is thought that RBS's backing accounted for up to 15% of its total budget.
Williams founder Frank Williams remained optimistic that the team will be able to find a new sponsor. He stated that there was a 95% chance that the team will secure a new deal within the next year.
He told BBC Sport: "We have to work hard to find them, keep them and look out for others all the time."