The agencies involved are Cake, Grey Global, JWT, Lowe Worldwide, Ogilvy & Mather, Wieden & Kennedy and Young & Rubicam. Each will create an ad tackling a specific issue contributing to the spread of the disease, such as unsafe sex, social stigma and gender inequality.
Each spot will premier on National Aids Day on 1 December, which this year marks 25 years since the syndrome was first diagnosed.
The agencies will produce their work pro bono and make them available rights-free to media outlets worldwide.
MTV Networks, whose vice-chairman, Bill Roedy, is the chairman of the Global Media Aids Initiative, the charity organisation that is running the project, will offer the spots to all of its 50 global channels. He said: "Media has a critical role in this fight against Aids and must do more. These agencies have some of the best creative minds in the world. This effort will make a real difference."
Sir Martin Sorrell, the chief executive of WPP, said: "The test of talent in our business is the power to persuade. There has never been a tougher test than this one - nor one more critical."