The Department of Trade and Industry, which has traditionally been the "sponsor" of the ad industry, is to share the task with the Department of Culture, Media and Sport.
The joint sponsorship is a recognition of the role the DCMS has played in fostering the development of Britain's creative industries.
But the change could cause confusion in the ad world about which Whitehall department to lobby. Industry leaders see merit in having a "one-stop shop" where they can make representations.
Although there have been concerns about the DTI's dual role in being responsible for advertising and consumer protection, the Advertising Association was worried about a plan in the Liberal Democrats' election manifesto to abolish the DTI. One upside of the shake-up for the advertising industry is that Tessa Jowell, the culture secretary, has been sceptical about banning junk-food ads aimed at children.
The day-to-day responsibility for advertising at the DCMS will be handed to James Purnell, the new minister for media and tourism and a former aide to Tony Blair.
The DCMS and the DTI will also share responsibility for computer games, publishing and the Design Council. The council's chairman, Brian Cox, is heading a review into how creative industries can help other businesses compete in the global economy.