The media company bid for the festival following the decision to sell by its 71-year-old owner and chairman, Roger Hatchuel.
Emap can expect to make an income of around 20 million euros a year from the sale of delegate passes and entries for the event. Entries for the 2004 festival reached more than 18,700, up 14 per cent on the previous year, and there were around 8,000 delegates.
Hatchuel, who has run the festival for 17 years and was behind its relocation from Venice to Cannes, decided to sell after it became clear the business would not remain a family concern.
His son, Romain, quit his position as the festival's chief executive two years ago and now runs a branding agency called The Key with Philippe Starck.
Father and son are said to have fallen out over Hatchuel senior's plans to relocate the festival's headquarters from London to Paris.
Terry Savage, the festival's chief executive, will continue in the same role following the Emap acquisition.
Derek Carter, the chief executive of Emap Communications, said: "Working with the international advertising community, it is our intention to ensure that the Cannes festival continues to reflect the rich diversity of this exciting marketplace."